Erythromycin 0.5% ophthalmic ointment
Macrolide antibiotic ointment (E-Mycin)
| Bacterial conjunctivitis | 1 cm ribbon in affected eye(s) up to 6×/day × 5–7 days |
| Blepharitis | Apply to lid margins BID–TID |
| Neonatal prophylaxis | 1 cm ribbon in both eyes once at birth |
| Retail price | ~$12–20 / 3.5 g tube (generic; GoodRx ~$11.79) |
⚠ Ongoing shortage since 2022. Consider AzaSite or moxifloxacin as alternatives when unavailable. CDC and AAO recommend AzaSite as erythromycin substitute.
Azithromycin 1% (AzaSite)
Macrolide drops — erythromycin alternative
| Bacterial conjunctivitis | 1 drop BID × 2 days, then QD × 5 days |
| Blepharitis | 1 drop BID × 2 days, then QD |
| Min age | ≥1 year |
| Retail price | ~$205–260 / 2.5 mL (no generic); EyeRx Direct program ~$60; GoodRx ~$205 |
⚠ In shortage (2026). Distributed exclusively through EyeRx Direct specialty pharmacy (azasite.com) — not available at most retail pharmacies. No FDA-approved generic.
Tobramycin 0.3% (Tobrex)
Aminoglycoside antibiotic
| Mild–moderate infection | 1–2 drops Q4H; or ointment 2–3×/day |
| Severe infection | 1–2 drops Q1H until improved, then taper |
| Forms | 0.3% solution (5 mL) and 0.3% ointment (3.5 g) |
| Retail price | ~$25–55 / 5 mL drops (generic); ointment ~$30–60 |
Good gram-negative coverage including Pseudomonas. Preferred for CL-related keratitis alongside fluoroquinolones.
Tobramycin / Dexamethasone (Tobradex)
Antibiotic + steroid combination
| Infection + inflammation | 1–2 drops Q4–6H; or ointment TID–QID |
| Post-op (mild) | QID × 1–2 weeks |
| Tobradex ST | 0.05%/0.1% suspension — lower tobramycin concentration; brand ~$149–309 |
| Retail price | Brand drops ~$214/5 mL; brand ointment ~$361–395/3.5 g; generic (tobramycin-dexa) ~$28–30 with GoodRx |
⚠ Monitor IOP — steroid-response glaucoma risk. Avoid in viral keratitis. Generic suspension available; ointment is brand-only.
Moxifloxacin 0.5% (Vigamox)
4th-generation fluoroquinolone
| Bacterial conjunctivitis | TID × 7 days |
| Bacterial keratitis | Q1H while awake × 2 days → Q2H × 3 days → QID until resolved |
| Post-procedure prophylaxis | QID × 7 days |
| Retail price | ~$20–45 / 3 mL (generic available; GoodRx ~$18–25) |
Preservative-free. Excellent gram-positive and gram-negative coverage including MRSA. First-choice for bacterial keratitis and post-op prophylaxis.
Ciprofloxacin 0.3% (Ciloxan)
Fluoroquinolone — drops & ointment
| Bacterial conjunctivitis | Drops: 1–2 drops Q2H × 2 days, then Q4H × 5 days Ointment: ½ in TID × 2 days, then BID × 5 days |
| Corneal ulcer | Q15 min × 6H → Q30 min × 18H → Q1H day 3 → Q4H days 4–14 |
| Retail price | ~$10–20 / 5 mL drops (GoodRx ~$10.57); ointment ~$30–50 |
Most affordable fluoroquinolone. Corneal white precipitates can occur with intensive dosing — benign, resolve on discontinuation.
Ofloxacin 0.3% (Ocuflox)
3rd-generation fluoroquinolone
| Bacterial conjunctivitis | 1–2 drops Q2–4H × 2 days, then QID × 5 days |
| Corneal ulcer | Q30 min while awake + Q4–6H at night × 2 days → QH while awake × 5 days → QID |
| Retail price | ~$15–30 / 5 mL (generic) |
Broader spectrum than ciprofloxacin; slightly less MRSA activity than moxifloxacin. Good cost-efficacy balance.
Besifloxacin 0.6% (Besivance)
Ophthalmic-only fluoroquinolone — lower resistance
| Bacterial conjunctivitis | 1 drop TID (8H apart) × 7 days; shake well |
| Unique advantage | Not used systemically → lower resistance rates vs. other FQs |
| Retail price | ~$150–200 / 5 mL suspension (brand only) |
Reserve for resistant organisms or when MRSA/MRSE is suspected. No generic available.
Prednisolone acetate 1% (Pred Forte)
Topical corticosteroid
| Anterior uveitis | Q1H while awake (acute) → taper weekly |
| Post-op | QID × 1 wk → TID × 1 wk → BID × 1 wk → QD × 1 wk |
| Episcleritis | QID × 5–7 days |
| Retail price | ~$15–30 / 5 mL (generic); brand ~$50–80. Shake well. |
⚠ Monitor IOP. Risk of steroid-response glaucoma and PSC cataract with prolonged use. Avoid in HSV keratitis without antiviral cover.
Loteprednol etabonate 0.5% (Lotemax)
Retrometabolic steroid — lower IOP risk
| Post-op inflammation | QID beginning 24H pre-op, × 2 weeks post-op |
| Seasonal allergy (0.2% Alrex) | QID |
| Lotemax SM 0.38% gel | BID — better retention, less blurring |
| Retail price | ~$50–120 brand; limited generics available |
Preferred over prednisolone in steroid responders or for long-term use — metabolized locally before significant systemic absorption.
Ketorolac 0.5% (Acular)
Topical NSAID
| Allergic conjunctivitis | QID up to 2 weeks |
| Post-op pain/inflammation | QID × 2 weeks |
| CME prevention | QID starting 1 day pre-op, × 4 weeks post-op |
| Retail price | ~$15–35 / 5 mL (generic) |
⚠ Risk of corneal melting with prolonged use or compromised epithelium. Caution in contact lens wearers.
Olopatadine (Pataday)
Antihistamine / mast cell stabilizer
| 0.1% Patanol (Rx) | BID × up to 6 weeks; ~$20–40 Rx |
| 0.2% Pataday (OTC) | QD; OTC ~$15–22 |
| 0.7% Pataday Once (OTC) | QD — highest concentration; OTC ~$18–25 |
First-line for allergic conjunctivitis. Now OTC (0.2% and 0.7%). Insert 10 min before contact lenses.
Cyclopentolate 1% (Cyclogyl)
Cycloplegic / mydriatic
| Dose | 1–2 drops; repeat in 5 min if needed |
| Onset | 25–75 min (peak cycloplegia) |
| Duration | 6–24 hr (cycloplegia); up to 24 hr (mydriasis) |
| Pediatric | 0.5% for infants <1 yr; 1% for children ≥1 yr |
| Retail price | ~$15–25 / 15 mL (generic) |
⚠ CNS toxicity risk in infants/children (irritability, hallucinations, ataxia). Use lower concentration and limit drops.
Tropicamide 1% (Mydriacyl)
Short-acting mydriatic
| Dose | 1–2 drops; repeat in 5 min |
| Onset | 20–40 min |
| Duration | 4–8 hr (mydriasis); poor cycloplegia |
| Retail price | ~$12–18 / 15 mL (generic) |
Often combined with phenylephrine 2.5% for enhanced dilation, especially in dark irides.
Phenylephrine 2.5% / 10%
Sympathomimetic mydriatic
| Dose | 1–2 drops; may repeat ×1 |
| Onset / Duration | 15–20 min / 4–6 hr |
| Use | Adjunct to tropicamide; 2.5% preferred over 10% |
| Retail price | ~$10–20 / 5 mL |
⚠ Avoid 10% in children, elderly, CVD, or narrow angles. Risk of hypertensive crisis.
Atropine sulfate
Cycloplegic / myopia control
| Cycloplegia | 1% — 1 drop TID × 3 days before exam; duration 7–14 days |
| Myopia control | 0.01%–0.05% — 1 drop QHS OU |
| Retail price | ~$40–80/mo compounded (0.01–0.05%); standard 1% ~$15–30 |
See Myopia control tab for full protocol. Low-dose 0.01% has minimal side effects with good efficacy.
Proparacaine 0.5%
Topical anesthetic
| Dose / Onset / Duration | 1–2 drops / 30 sec / 10–15 min |
| Use | Tonometry, foreign body removal, gonioscopy, CL fitting |
| Retail price | ~$12–20 / 15 mL (generic) |
⚠ Never prescribe for home use — chronic use causes corneal epithelial toxicity and erosion.
Sodium fluorescein
Diagnostic dye — staining & tonometry
| Strips | Touch to inferior fornix with 1 drop saline or proparacaine |
| Tonometry (Fluress) | NaFl 0.25% + proparacaine 0.5% — 1 drop; ~$15 / 5 mL |
| Staining patterns | Abrasion: bright green; dendrite: branching; Seidel: fluorescein flow |
Use cobalt blue filter + yellow Wratten #12 filter for enhanced staining visualization.
Dorzolamide 2% / Timolol 0.5% (Cosopt)
CAI + beta-blocker combo — IOP lowering
| Dose | 1 drop BID |
| IOP reduction | ~25–30% reduction |
| Retail price | ~$30–60 / 10 mL (generic; Cosopt PF preservative-free also available) |
⚠ Timolol: avoid in asthma, COPD, bradycardia, heart block. Dorzolamide: caution in sulfa allergy. Counsel on systemic absorption.
Latanoprost 0.005% (Xalatan)
Prostaglandin analogue — IOP lowering
| Dose | 1 drop QHS — evening dosing critical for efficacy |
| IOP reduction | ~25–33% reduction |
| Onset / Peak | 3–4 hr / 8–12 hr |
| Retail price | ~$15–30 / 2.5 mL (generic); brand ~$80–120 |
Counsel on: iris pigmentation change, lash growth, periorbital fat atrophy. Refrigerate unopened; opened bottles room temp × 6 weeks.
Myopia Tools & Links
External calculators and resources for myopia management
BHVI Myopia Calculator
Brien Holden Vision Institute — risk prediction and management planning tool
Estimates a child's likely myopia progression based on age, current refraction, and ethnicity. Helps set realistic expectations with parents and guides treatment decisions.
GMAC Myopia Awareness Toolkit
Global Myopia Awareness Coalition — patient education and practice resources
Free resources for practitioners and patients including handouts, infographics, and guidance on discussing myopia risk and control options. Useful for chairside education and waiting room materials.
Myopia Risk Factors
When to initiate myopia control — early intervention saves axial length
The case for early intervention
Don't wait for myopia — act on risk
Key Concept▾
Each diopter of myopia increases lifetime risk of myopic maculopathy, retinal detachment, glaucoma, and cataract. The earlier myopia onset, the higher the final prescription. Intervention before myopia onset can delay or prevent it entirely.
| Onset at age 7 | Expected final Rx: –6.00 to –8.00 D or worse |
| Onset at age 10 | Expected final Rx: –3.00 to –5.00 D |
| Onset at age 12 | Expected final Rx: –1.50 to –3.00 D |
| Stabilization | Typically by late teens; later in East Asian populations |
Target: keep final Rx above –3.00 D to stay in the lower-risk range. Every –1.00 D prevented = meaningfully lower lifetime pathology risk. Don't wait for progression — intervene at first sign of risk.
Ref: IMI Risk Factors for Myopia, Morgan et al., IOVS 2021;62(5):3. Bullimore & Brennan, Optom Vis Sci 2019 (axial length & pathology risk).
High-risk profile — initiate treatment now
Any one of these warrants immediate discussion
High Risk▾
- Both parents myopic — 6–8× higher risk vs no myopic parents; highest single risk factor
- One myopic parent + Asian ethnicity — compounding risk; initiate at first visit
- Already myopic (any amount) — start control immediately, especially if age <10
- Rapid progression ≥0.75 D/year — accelerated axial elongation underway
- Axial length >24.0 mm in a child — already elongated; treat aggressively
- Low hyperopic reserve for age — <+0.75 D at age 6–7 = high myopia conversion risk
- Esophoric child with high AC/A — nearwork-driven mechanism; plus lenses + myopia control
⚠ Do not wait for 0.50 D progression before starting. By then, axial elongation has already occurred. Risk-factor counselling and treatment initiation at the first sign of risk is best practice.
Ref: Jones-Jordan et al., CLEERE Study, IOVS 2010;51:115. Németh et al., Eur J Ophthalmol 2021 (EU management consensus).
Moderate-risk profile — counsel and monitor closely
Strong case for early treatment; discuss options
Moderate Risk▾
- One myopic parent — 3× higher risk; discuss myopia control proactively
- Significant nearwork (>3 hrs/day screen/reading) without outdoor balance
- <60–90 min outdoor time per day — reduced retinal dopamine; modifiable risk
- Progressive hyperopia reduction without myopia yet — watch axial length closely
- Axial length growing >0.2 mm/year — subclinical but concerning elongation rate
- East Asian ethnicity — population prevalence up to 80–90% in urban areas; lower threshold to treat
⚠ Start the myopia control conversation with parents at this stage. Lifestyle modification (outdoor time, near work breaks) is low-cost and should begin immediately. Consider starting optical myopia control if >2 moderate risk factors present.
Ref: IMI Clinical Management Guidelines, Gifford et al., IOVS 2019;60:M184. WHO–Brien Holden Vision Institute report 2015.
Pre-myopic intervention — treating before –0.50 D
Emerging evidence supports acting earlier than the prescription suggests
Pre-Myopic▾
Traditional practice was to wait until a child was "officially" myopic (–0.50 D or more) before initiating control. Emerging evidence supports intervention earlier, particularly in high-risk children.
Indicators for pre-myopic treatment:
- Cycloplegic refraction <+0.75 D at age 6–7 (used up their hyperopic buffer)
- Axial length >23.5 mm before myopia onset
- Axial elongation rate >0.2 mm/year even while still hyperopic
- Both parents myopic + significant nearwork + limited outdoor time
- Myopia in one eye only (anisomyopia developing) — treat both eyes
Options for pre-myopic or low myopia (<–0.50 D):
- Essilor® Stellest® Lenses — approved from –0.75 D; can prescribe at mild myopia threshold
- Low-dose atropine 0.01% — evidence for slowing axial elongation even pre-myopia; safest side effect profile
- Increased outdoor time — ≥90 min/day is low-cost and backed by strong evidence
- Near work modification — 20-20-20 rule; Harmon distance; posture correction
The LAMP study and other trials support low-dose atropine starting before –0.50 D in high-risk children. The risk of delaying treatment outweighs the risk of starting early.
Ref: Zadnik et al., JAMA Ophthalmol 2015;133:683 (hyperopic reserve). Yam et al., LAMP Study, Ophthalmology 2019;126:113.
Myopia control decision checklist
Quick chairside reference
Checklist▾
| Age | Under 10? Treat aggressively. 10–14? Still high priority. 14–18? Still worthwhile. |
| Family Hx | Both parents myopic → highest risk. One parent → moderate risk. No parents → baseline risk. |
| Current Rx | Already myopic → start now. Plano/low hyperope with risk factors → start pre-emptively. |
| Axial length | If measurable: >24.0 mm = treat; growing >0.2 mm/yr = treat; monitor q6 months. |
| Lifestyle | Screen >3 hrs/day + <90 min outdoor → modifiable risk; counsel every visit. |
| Ethnicity | East Asian → lower threshold to initiate. High ambient prevalence = environmental pressure. |
| Progression rate | ≥0.50 D/yr → escalate treatment. ≥0.75 D/yr → maximum intervention. |
First-line for most children: Essilor® Stellest® Lenses (spectacle wearers) or MiSight (CL candidates). Add 0.01% atropine QHS for high-risk or rapid progressors. Document discussion with parents at every visit.
Ref: IMI Clinical Management Guidelines, Gifford et al., IOVS 2019. AAO Pediatric Eye Evaluations PPP 2022.
Myopia Risk Assessment
Answer all six to classify risk and whether to begin myopia management. Educational tool — not a substitute for clinical judgment.
1. Age
2. Current refractive status (cycloplegic)
3. Parental myopia
4. Near work (reading/screens, hrs/day)
5. Time outdoors (hrs/day)
6. Ethnicity
Risk factors and their relative importance are based on the IMI Risk Factors for Myopia report (Morgan et al., IOVS 2021), the CLEERE Study (Jones-Jordan et al., IOVS 2010), and Zadnik et al. (JAMA Ophthalmol 2015) on hyperopic reserve. The point weighting is a clinical construction informed by these sources, not a validated instrument; near work is weighted lightly given its debated independent effect. Use alongside clinical judgment.
Highest published spectacle efficacy
Essilor® Stellest® Lenses
H.A.L.T. technology — highest-efficacy spectacle lens for myopia control
H.A.L.T.▾
| Efficacy | 71% reduction in myopia progression vs. single-vision lenses (2-year clinical trial); clinically proven to reduce axial elongation by 53% over 2 years |
| Technology | H.A.L.T. — 1,021 aspherical lenslets arranged in a constellation pattern, creating a volume of myopic defocus signal |
| Ideal candidate | Myopic and high-risk pre-myopic children in spectacles. Minimal adaptation period — most children are comfortable from day one |
| Wearing schedule | ≥10 hrs/day, 6+ days/week — higher efficacy with more hours worn |
| Rx range | Sphere –0.75 to –10.00 D; cylinder up to –4.00 D |
| Availability | Lab-processed lens; available through major optical wholesale distributors |
Essilor® Stellest® Lenses demonstrated 71% slowing of myopia progression in children wearing lenses ≥10 hrs/day, 6+ days/week — the highest published efficacy of any spectacle lens option. Ideal first choice for children where atropine or contact lens use is not preferred.
Ref: Bao et al., Br J Ophthalmol 2022;106:1171 (H.A.L.T., 2-yr data). Bao et al., JAMA Ophthalmol 2022;140:472.
Low-dose atropine
Evidence-based pharmacological intervention
Pharmacological▾
| Dose | 0.01%–0.05% atropine, 1 drop QHS OU |
| Efficacy | 0.01%: ~50–60% slowing; 0.05%: ~60–70% slowing |
| Rebound | Minimal at 0.01% vs. higher doses |
| Side effects | Minimal at 0.01% (slight mydriasis, mild photophobia) |
| Duration | Until ~18 yrs or ≥2 yrs of stability |
| Cost | ~$40–80/mo compounded; not commercially available in US |
Start at 0.01%. If progressing >0.50 D/yr, step up to 0.025% or 0.05%. Annual side-effect review.
Ref: Yam et al., LAMP Study Phase 2, Ophthalmology 2020;127:910. ATOM2, Chia et al., Ophthalmology 2012;119:347.
Orthokeratology (Ortho-K)
Overnight corneal reshaping lenses
Optical▾
| Efficacy | ~40–60% reduction in axial elongation |
| Ideal candidate | Myopia –1.00 to –6.00 D, astigmatism ≤1.50 D, motivated child/parent |
| Best age | 6–10 years old |
| Follow-up | 1 day → 1 week → 1 month → q3–6 months |
| MK risk | ~7–8 per 10,000 patient-years |
⚠ Rigorous hygiene compliance essential. Use H2O2 care system. Thorough patient and parent education is critical.
Ref: Cho & Cheung, ROMIO Study, IOVS 2012;53:7077. Sun et al., meta-analysis, PLoS One 2015.
Myopia control soft contact lenses
MiSight, Acuvue Abiliti, NaturalVue
Optical▾
| MiSight 1 Day | ~59% reduction; FDA-approved ages 8–12; DISC design (CooperVision) |
| Acuvue Abiliti | ~52% reduction; EDOF + peripheral ADD (J&J) |
| NaturalVue | Extended depth of focus; ~1D add equivalent (Visioneering) |
| Wearing schedule | ≥10 hrs/day, 6+ days/week |
Compliance is the strongest predictor of outcome. Document hours worn per day at every visit.
Ref: Chamberlain et al., MiSight 3-yr, Optom Vis Sci 2019;96:556. Walline et al., BLINK Study, JAMA 2020;324:571.
Other spectacle options
DIMS (MiyoSmart), PALs, bifocals
Optical▾
| DIMS (MiyoSmart) | ~52% reduction; honeycomb defocus islands (Hoya) |
| PALs | Limited evidence; not recommended as primary myopia control intervention |
| Executive bifocal | +2.00 add; greater effect in esophoric children |
For highest spectacle efficacy, consider Essilor® Stellest® — see featured card above.
Ref: Lam et al., DIMS/MiyoSmart, Br J Ophthalmol 2020;104:363. IMI Clinical Management Guidelines 2019.
Lifestyle & environmental factors
Adjunct recommendations for all patients
Lifestyle▾
- Outdoor time: ≥90–120 min/day — strongest protective factor; retinal dopamine release
- Near work breaks: 20-20-20 rule — every 20 min, look 20 ft away for 20 sec
- Reading distance: Harmon distance (elbow to middle knuckle)
- Axial length monitoring: Zeiss IOLMaster, Topcon Myah, or Heidelberg Myopia Watch every 6–12 months
Ref: He et al., outdoor time RCT, JAMA 2015;314:1142. IMI Risk Factors for Myopia, IOVS 2021.
CL Parameters
Parameters & pricing. Tap a lens for full power/cylinder/axis/add ranges. Filters combine — select Toric + Multifocal to find multifocal torics.
Lens type (combinable)
Replacement schedule
Ref: Parameters compiled from manufacturer package inserts & fitting guides (J&J Vision, Alcon, CooperVision, Bausch + Lomb), 2024–25. Always verify exact power/cylinder/axis availability and current pricing with the manufacturer or your distributor before ordering — parameters change with product updates. Pricing is approximate US retail. Toric axis availability varies: common axes (near 90° and 180°) are widely stocked, while oblique axes (30–60°, 120–150°) and high-cylinder combinations are often limited or made-to-order — always confirm the exact axis before ordering.
Parks 3-Step Test
Parks-Bielschowsky — isolate a paretic cyclovertical muscle
Select all three steps. The paretic muscle will appear automatically.
Step 1 — Which eye is hypertropic in primary gaze?
Step 2 — Does the hypertropia increase in right or left gaze?
Step 3 — Does the hypertropia increase on right or left head tilt? (Bielschowsky)
Plaquenil Risk Calculator
Hydroxychloroquine toxicity screening — AAO 2016 guidelines
Plaquenil (Hydroxychloroquine) Toxicity Risk Calculator
AAO 2016 guidelines — daily dose & Macular risk assessment
Calculator▾
AAO screening recommendations: Baseline exam within 1 year of starting. Annual screening after 5 years (or sooner with risk factors). Preferred: 10-2 VF + SD-OCT. mfERG optional adjunct.
Retinal Disease
Inherited retinal dystrophies, fundus exam approach, key pathology
Inherited retinal dystrophies — quick reference
RP, Stargardt, Best, cone dystrophy, CSNB
IRD▾
| Retinitis Pigmentosa (RP) | Rod-cone dystrophy; bone spicule pigmentation; attenuated vessels; waxy disc pallor; night blindness → peripheral field loss → central loss. ERG: extinguished rods early. |
| Stargardt disease | ABCA4 mutation; macular atrophy; pisciform flecks; dark choroid on FA; onset teens–30s; presents as decreased VA with normal-appearing fundus early. |
| Best vitelliform | BEST1 mutation; "egg yolk" macular lesion; EOG abnormal (Arden ratio <1.5) even in carriers; VA may be preserved for years. |
| Cone dystrophy | Central vision loss > peripheral; photophobia; color vision affected early; ERG: reduced photopic, relatively preserved scotopic. |
| CSNB | Congenital stationary night blindness; non-progressive; ERG: absent or reduced scotopic b-wave; may present with nystagmus. |
| Choroideremia | X-linked; progressive degeneration of RPE + choriocapillaris + photoreceptors; scalloped peripheral atrophy; male patients most affected. |
Key: refer all suspected IRD for genetic testing (Blueprint Genetics, Invitae). Low vision referral early. Gene therapy trials available for RPE65, RPGR, CNGB3.
Ref: AAO Retina/Vitreous BCSC 2023–24. Duncan et al., IRD consensus, Ophthalmology 2018;125:1710.
Fundus exam approach for retinal pathology
Systematic evaluation at the slit lamp and indirect
Technique▾
Systematic approach (posterior pole first):
- Disc: C/D ratio, rim color, neuroretinal rim integrity (ISNT rule), disc hemorrhage, peripapillary atrophy
- Macula: foveal reflex, drusen, pigment changes, fluid, exudate, hemorrhage, atrophy
- Vessels: A/V ratio (normal 2:3), nicking, caliber changes, neovascularization
- Periphery: lattice, holes, tears, detachment, pigment, ora serrata
Indirect ophthalmoscopy indentation landmarks:
- Ora serrata: ~7 mm posterior to limbus (temporal), ~6 mm nasal
- Vitreous base: straddles ora ~2 mm anterior + 3 mm posterior
⚠ New floaters + flashes: rule out PVD, retinal tear, or detachment. Dilate same day. Refer if tear or RD found.
Ref: AAO Comprehensive Adult Medical Eye Evaluation PPP 2020. Kanski's Clinical Ophthalmology, 9th ed.
Retinal vascular occlusions
CRVO, BRVO, CRAO, BRAO — presentation and management
Urgent▾
| CRAO | Sudden painless monocular vision loss; cherry red spot; retinal whitening; box-carring of vessels. <4.5 hr window — urgent ER referral for thrombolysis consideration. Workup: carotid US, echo, CBC, ESR/CRP (rule out GCA). |
| BRAO | Sectoral whitening; may be asymptomatic if peripheral. Embolic workup essential (Hollenhorst plaque = carotid source). |
| CRVO | "Blood and thunder" fundus; disc edema; tortuous dilated veins all 4 quadrants. Ischemic vs non-ischemic: ≥10 disc areas of capillary non-perfusion on FA = ischemic → higher NV risk. OCT angiography can also help assess. Monthly anti-VEGF if CME present. |
| BRVO | Sectoral hemorrhage; flame hemorrhages follow nerve fiber layer. CME common. Anti-VEGF first-line for vision loss from CME. |
Ref: AAO Retinal Vein Occlusion PPP 2019. CRAO scientific statement, Stroke 2021;52:e282.
Diabetic retinopathy staging
ETDRS classification and referral thresholds
Staging▾
| No DR | No abnormalities; annual exam |
| Mild NPDR | Microaneurysms only; annual |
| Moderate NPDR | More than mild; less than severe; q6 months |
| Severe NPDR | 4-2-1 rule: ≥20 intraretinal hemorrhages in 4 quads, venous beading in ≥2 quads, IRMA in ≥1 quad; refer retina q3–4 months |
| PDR | Neovascularization of disc/elsewhere; refer retina urgently. High-risk: NVD >1/4–1/3 disc area or any NVD with vitreous hemorrhage. |
| CI-DME | Center-involving diabetic macular edema: anti-VEGF first line. OCT essential for diagnosis. |
A1c >10%, rapid glucose lowering, hypertension, pregnancy, and renal disease all worsen DR progression. Document and co-manage with PCP.
Ref: AAO Diabetic Retinopathy PPP 2019. ETDRS Report No. 12, Ophthalmology 1991.
Age-Related Macular Degeneration
Staging, treatment guidelines, monitoring
AMD staging — AREDS classification
No AMD → early → intermediate → late
Staging▾
| No AMD | No drusen or small drusen only (<63 μm); no pigment changes |
| Early AMD | Medium drusen (63–124 μm) OR small drusen (<63 μm) with pigment abnormalities; no late AMD in either eye |
| Intermediate AMD | Large drusen (≥125 μm) and/or geographic atrophy not involving center; significant pigmentary changes; high 5-year risk |
| Late AMD | Geographic atrophy involving foveal center, OR neovascular AMD (wet/exudative) with CNV |
AREDS2 supplement (lutein 10mg + zeaxanthin 2mg + Vit C + Vit E + zinc) recommended for intermediate AMD or late AMD in one eye. Reduces progression risk by ~25%.
Ref: Ferris et al., AREDS classification, Ophthalmology 2013;120:844. AAO AMD PPP 2019.
Neovascular (wet) AMD — treatment
Anti-VEGF agents, dosing, monitoring
Treatment▾
| Bevacizumab (Avastin) | 1.25 mg/0.05 mL; off-label; most cost-effective; ~$50/injection |
| Ranibizumab (Lucentis) | 0.5 mg/0.05 mL; FDA approved; monthly or PRN; ~$1,200/injection |
| Aflibercept (Eylea) | 2 mg/0.05 mL; monthly ×3 then q8 weeks; ~$1,850/injection |
| Faricimab (Vabysmo) | Anti-VEGF-A + Ang-2; up to q16 weeks after loading; newest option |
| Brolucizumab (Beovu) | 6 mg; q12 weeks after loading; risk of intraocular inflammation |
Monitoring:
- OCT monthly during loading phase (3 monthly injections)
- PRN or treat-and-extend after stability achieved
- Watch for: subretinal fluid, intraretinal fluid (IRF worse prognosis than SRF), RPE detachment
Ref: AAO AMD PPP 2019. CATT Research Group, NEJM 2011;364:1897. Vabysmo/Faricimab TENAYA-LUCERNE, Lancet 2022.
Amsler grid & home monitoring
Patient instructions and conversion to ForeseeHome
Monitoring▾
- Amsler grid: 20 cm from face, one eye at a time, with reading correction. Report metamorphopsia, missing areas, new distortion immediately.
- ForeseeHome (Notal Vision): FDA-cleared home monitoring device for intermediate/late AMD. Detects conversion to wet AMD earlier than standard care. Medicare covered.
- Instruct patients: any new distortion or sudden vision change = call same day, do not wait for scheduled appointment.
⚠ New metamorphopsia in a known AMD patient = presumed CNV until proven otherwise. Same-day OCT ± FA referral.
Ref: AREDS2-HOME Study (ForeseeHome), Ophthalmology 2014;121:535.
Geographic atrophy (GA) — new treatments
Pegcetacoplan, avacincaptad pegol
Treatment▾
| Syfovre (pegcetacoplan) | Complement C3 inhibitor; 15 mg intravitreal injection; q25 or q50 days; FDA approved Feb 2023. Slows GA growth ~20–22%. |
| Izervay (avacincaptad pegol) | Complement C5 inhibitor; 2 mg monthly injection; FDA approved Aug 2023. Slows GA growth ~14–18%. |
First-ever approved treatments for GA. Neither restores vision — they slow progression. Refer to retina specialist for candidacy assessment. Risk of conversion to neovascular AMD with use (~7%).
Ref: OAKS/DERBY (pegcetacoplan), Lancet 2023. GATHER1/2 (avacincaptad), Ophthalmology 2023.
Common OCT Findings
Macular OCT interpretation — key patterns and what they mean
Macular OCT layers — quick reference
What each layer tells you
Reference▾
| ILM | Inner limiting membrane — epiretinal membrane forms here |
| NFL/GCL/IPL | Inner layers — thinning in glaucoma, ischemia, macular degeneration |
| INL | Inner nuclear layer — cystoid spaces here = CME (diabetic, post-op, CRVO) |
| OPL/ONL | Outer layers — photoreceptors; thinning = degeneration |
| IS/OS junction (EZ line) | Ellipsoid zone — disruption = photoreceptor damage, AMD, retinal dystrophy |
| RPE | Retinal pigment epithelium — drusen sit between RPE and Bruch's membrane; RPE detachments appear as domed elevations |
| Bruch's membrane / CC | Choriocapillaris below RPE — CNV grows through Bruch's |
Ref: Staurenghi et al., IN•OCT consensus nomenclature, Ophthalmology 2014;121:1572.
Key OCT patterns — what to look for
Fluid, drusen, atrophy, membranes
Patterns▾
| Intraretinal fluid (IRF) | Cystoid spaces within retinal layers — DME, CRVO, ERM. Worse prognosis in AMD than SRF. |
| Subretinal fluid (SRF) | Hyporeflective space between photoreceptors and RPE — wet AMD, CSR, tractional RD |
| Sub-RPE fluid / PED | Dome-shaped RPE elevation — drusenoid PED (dry AMD), fibrovascular PED (wet AMD), serous PED (CSR) |
| ERM | Hyperreflective line on ILM; causes retinal folds, decreased VA, metamorphopsia; peel if VA ≤20/50 or symptomatic |
| VMT / MH | Vitreomacular traction: attached vitreous causing cystoid changes. Full-thickness macular hole: graded Stage 1–4 by OCT. Ocriplasmin (Jetrea) for VMT — note: discontinued in the US in 2023; pars plana vitrectomy remains definitive. Surgery for FTMH. |
| CSR | Central serous retinopathy: subretinal fluid, often spontaneous in young stressed males; detached neurosensory retina. Usually self-resolving 3–4 months. |
| Drusen | Small (<63μm), medium (63–124μm), large (≥125μm); soft drusen higher AMD risk; reticular pseudodrusen = high late AMD risk |
| EZ line disruption | Photoreceptor damage — in AMD, dystrophies, laser scars; correlates with VA |
Ref: Staurenghi et al., IN•OCT consensus, Ophthalmology 2014. AAO Retina BCSC 2023–24.
RNFL OCT — glaucoma interpretation
Deviation maps, GCA, TSNIT curves
Glaucoma▾
- Red <1% (p<0.01) — outside normal limits; significant thinning
- Yellow 1–5% (p<0.05) — borderline; monitor closely
- Green >5% — within normal limits
- Inferior > Superior > Nasal > Temporal — ISNT rule for rim; reversed for RNFL (inferior thickest)
- GCA (ganglion cell analysis) — detects early glaucoma loss often before VF defect
- Progression analysis — compare serial scans; >4 μm change over time = significant
⚠ Thin central cornea, high myopia, and tilted discs can cause false positives on RNFL OCT. Always correlate with clinical exam and VF.
Ref: AAO Primary Open-Angle Glaucoma PPP 2020. Bussel et al., Br J Ophthalmol 2014;98:ii15.
Anterior Segment
Red eye DDx, eyelid disorders, vital dyes
Red Eye DDx
Conjunctivitis — bacterial vs viral vs allergic
Key distinguishing features
DDx▾
| Feature | Bacterial | Viral | Allergic |
| Discharge | Mucopurulent | Watery/serous | Watery/mucoid |
| Itch | Mild | Mild | Severe |
| Laterality | Often bilateral (starts uni) | Bilateral (starts uni) | Bilateral |
| Preauricular LN | Rare | Common | Absent |
| Follicles/Papillae | Papillae | Follicles | Papillae (giant) |
| Tx | FQ drops (moxifloxacin) | Supportive; cold compress | Olopatadine; avoid allergen |
⚠ Hyperacute purulent discharge = gonorrheal conjunctivitis (N. gonorrhoeae) — urgent corneal involvement risk. Same-day referral + systemic antibiotics.
Ref: AAO Conjunctivitis PPP 2018. Azari & Barney, JAMA 2013;310:1721.
Episcleritis vs scleritis
Key clinical differences and management
DDx▾
| Feature | Episcleritis | Scleritis |
| Pain | Mild, if any | Severe, boring, nocturnal |
| Color | Bright red/salmon | Deep violaceous/blue-red |
| Blanching with phenylephrine | Yes — blanches | No — does not blanch |
| Scleral edema | None | Present (nodular or diffuse) |
| Systemic association | Usually idiopathic | 50% — RA, IBD, GPA (Wegener's), SLE |
| VA affected | No | May be (posterior scleritis) |
| Treatment | Oral NSAIDs; topical steroids | Oral NSAIDs; systemic steroids; immunosuppression; refer rheum |
⚠ Posterior scleritis: pain + choroidal folds + exudative RD + disc edema on OCT/B-scan. Often missed. Order B-scan and refer urgently.
Ref: Watson & Hayreh classification, Br J Ophthalmol 1976;60:163. AAO External Disease BCSC 2023–24.
Other red eye causes
Subconjunctival hemorrhage, pinguecula, pterygium, dry eye, CL-related
DDx▾
| Subconjunctival hemorrhage | Bright red, well-demarcated; no pain; usually benign; resolves 1–2 weeks. Recurrent: check BP, coagulation. |
| Pinguecula/Pterygium | Pinguecula: yellow-white conjunctival deposit; pterygium: fibrovascular growth onto cornea. Surgery if threatening visual axis or >3 mm onto cornea. |
| Dry eye | Diffuse injection, worse PM; TBUT <5 sec; inferior SPK on fluorescein; treat underlying cause. |
| Contact lens-related | GPC (giant papillary conj.): upper tarsal cobblestones; reduce lens wear, switch modality. CLPU (contact lens peripheral ulcer): peripheral sterile infiltrate; off lenses 1–2 weeks + FQ drops. |
| Anterior uveitis | Ciliary flush (perilimbal injection); pain; photophobia; cells + flare in AC; KPs on corneal endothelium. Treat: prednisolone acetate + cycloplegic. |
Ref: AAO External Disease and Cornea BCSC 2023–24. Cronau et al., Am Fam Physician 2010;81:137.
Eyelid Disorders
Hordeolum vs chalazion vs other lid lesions
Differential diagnosis and treatment
DDx▾
| External hordeolum (stye) | Acute, painful, tender; Zeis/Moll gland; points externally. Warm compresses; topical FQ if cellulitis. Resolves in days. |
| Internal hordeolum | Meibomian gland abscess; points internally on palpebral conjunctiva; more painful. Warm compresses; oral antibiotics if spreading. |
| Chalazion | Chronic, non-tender lipogranuloma; Meibomian gland; firm nodule. Warm compresses 4–6 weeks; intralesional triamcinolone 0.1–0.2 mL; I&C if persistent >6 weeks. Biopsy if recurrent (r/o sebaceous cell carcinoma). |
| Preseptal cellulitis | Periorbital erythema + swelling; no proptosis; no restricted motility; no pain with eye movement. Oral augmentin; CT if not improving or orbital involvement suspected. |
| Orbital cellulitis | Proptosis + restricted motility + pain with EOM + fever. CT orbits urgently. IV antibiotics; admit. |
Ref: AAO Blepharitis PPP 2018. Lindsley et al., Cochrane Review 2017 (chalazion).
Ptosis — classification and workup
Aponeurotic, myogenic, neurogenic, mechanical
Neuro▾
| Aponeurotic | Most common; dehiscence of levator aponeurosis; high lid crease; good levator function. Involutional or post-op/CL wear. |
| Myogenic | CPEO, myasthenia gravis, myotonic dystrophy. Variable ptosis (MG: worse PM, fatigue test positive, ice pack test). |
| Neurogenic | CN III palsy (ptosis + "down and out" + +/- mydriasis); Horner's (partial ptosis + miosis + anhidrosis) |
| Mechanical | Mass effect — chalazion, tumor, dermatochalasis |
MRD1: margin-reflex distance (normal ≥3.5 mm). Levator function: poor <4 mm, fair 5–7 mm, good ≥8 mm.
Ref: AAO Oculoplastics BCSC 2023–24. Finsterer, Aesthetic Plast Surg 2003;27:193.
Blepharitis — anterior vs posterior
Classification, grading, treatment
Anterior Seg▾
| Anterior blepharitis | Lid margin debris, crusting at lash bases; staphylococcal (collarettes) or seborrheic (greasy scales). Lid hygiene + dilute baby shampoo scrubs; FQ ointment if bacterial component. |
| Posterior blepharitis (MGD) | Meibomian gland dysfunction; inspissated secretions; foamy tear film; telangiectatic lid margins. Warm compresses + lid massage; azithromycin drops; oral doxycycline 50–100 mg QD × 3 months; LipiFlow. |
| Demodex blepharitis | Cylindrical dandruff (sleeves) around lash bases; worse in older patients. Tea tree oil lid scrubs; lotilaner (Xdemvy) 0.25% BID × 6 weeks — first FDA-approved Demodex treatment. |
Ref: AAO Blepharitis PPP 2018. Lotilaner (Xdemvy) Saturn-1/2, Ophthalmology 2023.
Vital Dyes
Fluorescein sodium
Corneal staining, tonometry, contact lens fitting
Diagnostic▾
| Mechanism | Penetrates epithelial defects; does NOT stain intact epithelium. Fluoresces bright green under cobalt blue + Wratten #12 yellow filter. |
| Staining patterns | Abrasion: uniform bright green; Dendrite (HSV): branching with terminal bulbs; Acanthamoeba: pseudodendrites (no terminal bulbs); Superficial punctate keratitis: fine dots; Seidel test: aqueous dilutes fluorescein = streaming |
| Tear film TBUT | Instill, wait 30 sec, ask patient NOT to blink. Time from last blink to first break. <5 sec = abnormal. |
| Contact lens fit | RGP fitting: dark = bearing (touch), bright pooling = clearance, even pattern = alignment. Use high molecular weight fluorescein for SCL. |
| Dosing | Fluorescein strips (touch to lower fornix + saline) or Fluress drops (NaFl 0.25% + proparacaine 0.5%) |
Ref: AAO Cornea BCSC 2023–24. DEWS II Diagnostic Methodology, Wolffsohn et al., Ocul Surf 2017;15:539.
Rose bengal & lissamine green
Devitalized cell staining — dry eye and surface disease
Diagnostic▾
| Rose bengal | Stains devitalized and dead epithelial cells + mucus; also stains cells not protected by mucin. Intense pink/red. Causes stinging — warn patient. 1% solution or strips. Classic for Sjögren's (interpalpebral staining). |
| Lissamine green | Similar staining pattern to rose bengal but better tolerated; less stinging. Stains devitalized cells + mucus. Preferred in clinical practice over rose bengal. |
| Van Bijsterveld score | Divides conjunctiva + cornea into 3 zones (nasal conj, cornea, temporal conj); grade 0–3 per zone; max 9. Score ≥3.5 = abnormal (diagnostic of dry eye). |
| Oxford grading | Corneal fluorescein staining: 0–5 scale; grade ≥2 = significant epithelial disease. |
Use lissamine green with a red-free filter for best visualization. Wait 1–2 minutes after instillation for peak staining.
Ref: Van Bijsterveld, Arch Ophthalmol 1969;82:10. DEWS II Diagnostic Methodology, Ocul Surf 2017.
Grading Scales
Standardized grading for common ocular diseases
Lens/cataract grading — 1+ to 4+
Nuclear, cortical, PSC grading scale
Grading▾
Nuclear sclerosis (NS):
| 1+ | Faint yellow tint; clear lens; no visual impact; normal VA |
| 2+ | Definite yellow; mild glare; VA typically 20/20–20/40; patients may notice halos |
| 3+ | Deep amber/brown; moderate impact; VA 20/40–20/100; significant glare and contrast loss |
| 4+ | Dense brunescent/black; VA 20/100 or worse; often mature cataract; challenging surgery |
Cortical cataract (CC):
| 1+ | Peripheral spoke opacities <25% of lens; minimal visual impact |
| 2+ | Spokes 25–50%; may cause glare at night or in bright light |
| 3+ | Spokes 50–75%; significant glare; VA impact especially in bright conditions |
| 4+ | Spokes >75% or mature white cortex; severe VA impact |
Posterior subcapsular cataract (PSC):
| 1+ | Small granular opacity at posterior pole; symptomatic near vision loss disproportionate to VA |
| 2+ | Opacity <2 mm; near vision significantly affected; glare in bright light |
| 3+ | Opacity 2–3 mm; near and distance VA affected; debilitating glare |
| 4+ | Opacity >3 mm; severely reduced VA; marked glare; prompt surgical referral |
Referral threshold: VA ≤20/40 with functional complaint, OR significant glare/near vision loss affecting daily activities regardless of Snellen VA. PSC causes disproportionate near vision loss — don't rely on distance VA alone.
Ref: Chylack et al., LOCS III, Arch Ophthalmol 1993;111:831. AAO Lens & Cataract BCSC 2023–24.
Diabetic retinopathy — ETDRS & DRSS grading
Grading scale for clinical documentation
Grading▾
| 10 — No DR | No abnormalities |
| 20 — Very mild NPDR | Microaneurysms only |
| 35 — Mild NPDR | MAs + hard exudates/cotton wool spots/mild IRMA |
| 43/47 — Moderate NPDR | Approaching 4-2-1 rule |
| 53 — Severe NPDR | 4-2-1 rule met |
| 61/65 — Mild/Moderate PDR | NVE without high-risk characteristics |
| 71/75 — High-risk PDR | NVD ≥¼ disc area or vitreous hemorrhage |
| 81/85 — Advanced PDR | Traction RD / advanced fibrovascular proliferation |
Ref: ETDRS Report No. 10, Ophthalmology 1991;98:786. Wilkinson et al., Intl Clinical DR Scale, Ophthalmology 2003.
Angle grading — Shaffer & Van Herick
Gonioscopy and slit lamp angle assessment
Glaucoma▾
Shaffer gonioscopy grading:
| Grade 4 | 35–45° — wide open; ciliary body visible |
| Grade 3 | 25–35° — open; scleral spur visible |
| Grade 2 | 20° — narrow; trabecular meshwork visible |
| Grade 1 | 10° — very narrow; only Schwalbe's line visible; closure possible |
| Grade 0 | Closed — no angle structures visible; contact between iris and cornea |
Van Herick (slit lamp estimation):
| Grade 4 | Corneal thickness = peripheral AC depth; safe to dilate |
| Grade 2 | AC = ¼ corneal thickness; caution |
| Grade 1 | AC ≤ ¼ CT; do not dilate without gonioscopy |
Ref: Shaffer, Trans Am Acad Ophthalmol 1960. Van Herick et al., Am J Ophthalmol 1969;68:626.
Papilledema — Frisen scale
Grading disc edema severity
Grading▾
| Grade 0 | Normal disc |
| Grade 1 | Nasal border blurred; temporal margin normal; no elevation |
| Grade 2 | All margins blurred; elevation begins; vessels not obscured |
| Grade 3 | Marked elevation; vessels obscured at disc margin |
| Grade 4 | Severe elevation; vessels obscured >1 DD from margin |
| Grade 5 | Dome-shaped protrusion; vessels totally obscured on disc |
Ref: Frisén, J Neurol Neurosurg Psychiatry 1982;45:13.
Artificial Tears — Selection Guide
Choosing the right lubricant for the right patient
Artificial tear comparison by active ingredient
Viscosity, preservatives, best use cases
Reference▾
| Carboxymethylcellulose (CMC) | Refresh Tears, Optive — low–mid viscosity; preservative-free options available; good all-purpose lubricant |
| Hyaluronic acid (HA) | Blink, iVizia, Ocufresh — excellent retention; bioadhesive; preferred for moderate–severe dry eye; PF preferred |
| HP-Guar (Systane) | Systane Ultra, Balance — gels on contact with tear film; good for evaporative dry eye; may blur briefly |
| Polyethylene glycol / propylene glycol | Systane Complete, Soothe — lipid layer replacement; best for MGD/evaporative |
| Carbomer (gel) | GenTeal Gel, Refresh Celluvisc — high viscosity; best for nighttime use or severe aqueous deficiency; blurs vision |
| Mineral oil / lipid emulsion | Soothe XP, Refresh Optive Advanced — lipid supplement; best for MGD |
Ref: DEWS II Management & Therapy, Jones et al., Ocul Surf 2017;15:575.
Preservatives — when to go preservative-free
BAK toxicity, alternatives, clinical thresholds
Prescribing▾
- BAK (benzalkonium chloride): most common preservative; detergent effect — toxic with use >4×/day or in compromised epithelium
- PF threshold: go preservative-free if patient uses drops >4×/day, has moderate-severe dry eye, glaucoma (multiple preserved drops), or contact lens wear
- Alternatives to BAK: Purite (oxidative; less toxic), SofZia (ionic buffer; converts to non-toxic), NaDCC (Oxyd-1), PQ-1 (polyquaternium)
- PF unit-dose vials: Refresh Plus, Systane Ultra PF, Blink Tears PF — keep sterile 12 hrs after opening
- Multi-dose PF systems: Optive Fusion, iVizia — bottle with special filter; no BAK needed
Ref: Baudouin et al., Prog Retin Eye Res 2010;29:312. DEWS II Management, Ocul Surf 2017.
Artificial tear selection by dry eye type
Aqueous deficient vs evaporative
Treatment▾
| Aqueous deficient (Sjögren's) | PF HA drops QID–Q2H; PF gel at bedtime; consider autologous serum if severe; punctal plugs |
| Evaporative (MGD) | Lipid-based drops (Soothe XP, Systane Balance); warm compresses BID; oral omega-3; LipiFlow |
| Mixed mechanism | Combined approach: HA drops for aqueous + lipid drops for evaporation; treat MGD component aggressively |
| Contact lens wearers | Rewetting drops compatible with CL: Blink Contacts, Clerz Plus; PF preferred; rewet before inserting lenses |
Ref: DEWS II Management & Therapy, Jones et al., Ocul Surf 2017;15:575.
Targeted Dry Eye Pharmacotherapy
Prescription treatments for dry eye disease
Anti-inflammatory prescription dry eye drugs
Cyclosporine, lifitegrast, corticosteroids
Pharmacology▾
| Cyclosporine 0.05% (Restasis) | T-cell immunomodulator; BID; onset 3–6 months; burning on instillation common (use cold or refrigerate); generic available ~$100–150/mo |
| Cyclosporine 0.09% (Cequa) | Higher concentration; nanomicellar formulation; BID; better penetration; ~$350–500/mo; PF unit-dose |
| Lifitegrast 5% (Xiidra) | LFA-1/ICAM-1 antagonist; BID; faster onset than cyclosporine (onset ~2 weeks for symptoms); dysgeusia (metallic taste) common; ~$400–600/mo with coupon |
| Loteprednol 0.25% (Eysuvis) | Short-course steroid for acute flares; QID × 2 weeks; lower IOP risk than prednisolone; good bridge to immunomodulator |
| Perfluorohexyloctane (Miebo) | PFHO semi-fluorinated alkane; first non-aqueous DED treatment; QID; FDA approved 2023; reduces evaporation directly; ~$500/mo |
Ref: DEWS II Management, Ocul Surf 2017. Miebo (NOV03) GOBI/MOJAVE, Ophthalmology 2023.
Secretagogues & advanced therapies
Varenicline, autologous serum, scleral lenses, procedures
Pharmacology▾
| Varenicline nasal spray (Tyrvaya) | Nicotinic acetylcholine receptor agonist; nasal spray BID stimulates tear production via trigeminal-lacrimal reflex; onset 4 weeks; sneezing common; ~$400/mo |
| Autologous serum tears (AST) | Patient's own blood-derived; contains EGF, fibronectin, Vit A; 20–100% concentration; compounded; refrigerate; use within 3 months. For severe/refractory DED, neurotrophic keratitis, Stevens-Johnson. |
| Scleral lenses | Large-diameter GP lens vaults cornea; saline reservoir maintains constant hydration; excellent for severe DED, graft-versus-host disease (GvHD), Stevens-Johnson, post-LASIK DED |
| Intense Pulsed Light (IPL) | Reduces Demodex, meibomian gland inflammation; 4 sessions q3–4 weeks; good evidence for MGD-related DED |
| LipiFlow | Thermal pulsation of meibomian glands; single 12-min treatment; results last ~12 months; ~$800–1,200 per treatment |
Ref: Tyrvaya (varenicline) ONSET-1/2, Ophthalmology 2022. DEWS II Management, Ocul Surf 2017.
Nutraceuticals for Ocular Health
Evidence-based supplements for dry eye, AMD, and general ocular health
AREDS2 formula — AMD prevention
Evidence-based supplementation for intermediate AMD
Evidence-based▾
| Lutein | 10 mg/day — replaces beta-carotene (safer in smokers) |
| Zeaxanthin | 2 mg/day — macular pigment component |
| Vitamin C | 500 mg/day |
| Vitamin E | 400 IU/day |
| Zinc | 80 mg/day (zinc oxide) — lower dose (25 mg) option if GI side effects |
| Copper | 2 mg/day — taken with zinc to prevent deficiency |
Recommend AREDS2 for intermediate AMD or late AMD in one eye. Reduces 5-year progression risk by ~25%. Brands: PreserVision AREDS2, MacularProtect Complete, Ocuvite Eye Performance.
Ref: AREDS2 Research Group, JAMA 2013;309:2005.
Omega-3 fatty acids — dry eye
EPA/DHA dosing, evidence, product selection
Dry Eye▾
| Recommended dose | EPA + DHA ≥1,000 mg/day combined for dry eye; higher doses (2,000–3,000 mg) for moderate-severe |
| Re-esterified triglyceride form | Better absorbed than ethyl ester form; look for "rTG" on label |
| Products | PRN Dry Eye Omega Benefits (2,240 mg EPA+DHA rTG); HydroEye; Nordic Naturals Ultimate Omega |
| Evidence | DREAM study showed no difference vs placebo for omega-3 in DED — but used ethyl ester form. rTG form studies more positive. Reasonable to recommend as adjunct. |
| Flaxseed oil | ALA (alpha-linolenic acid) — plant-based but less efficiently converted to EPA/DHA; inferior to fish oil for ocular surface |
Ref: DREAM Study, NEJM 2018;378:1681. DEWS II Management, Ocul Surf 2017.
Other ocular health nutraceuticals
Astaxanthin, bilberry, saffron, B vitamins
Reference▾
| Astaxanthin | 6–12 mg/day; carotenoid; reduces eye fatigue, oxidative stress; some evidence for accommodative function; strong antioxidant |
| Bilberry (anthocyanins) | 160 mg BID; may improve night vision and retinal microcirculation; limited RCT evidence but widely used |
| Saffron (crocin/crocetin) | 20 mg/day; emerging evidence for early AMD protection; improves ERG responses in AMD patients |
| Vitamin D | Deficiency linked to dry eye, DR, and uveitis. Check 25-OH Vit D; supplement if <30 ng/mL. 2,000–4,000 IU/day typical. |
| B vitamins (B6, B9, B12) | Reduce homocysteine — elevated homocysteine associated with CRVO, CRAO, glaucoma, and AMD. B-complex supplements or targeted B6+B9+B12 combo. |
| Magnesium | Vasodilatory; may reduce vasospasm in NTG; some evidence for visual field stabilization. 300–400 mg/day magnesium glycinate. |
Ref: Lawrenson & Evans, Cochrane Review 2015. Piccardi et al., saffron RCT, Evid Based Complement Altern Med 2012.
Contact Lens Modality Selection
Matching the right lens type to the right patient
Modality decision framework
Daily vs monthly vs RGP vs specialty
Framework▾
| Daily disposable | Best compliance; no solutions; lowest infection risk; best for occasional wear, allergies, dry eye, children. Cost: ~$40–80/90pk. |
| Monthly/Biweekly SCL | Higher Dk silicone hydrogel options; lower cost for daily wear. Requires good compliance with case hygiene. Best for full-time wearers. |
| RGP (corneal) | Best optics; excellent for irregular corneas, high astigmatism, high myopia. Adaptation period 2–3 weeks. Durable (~1 yr). Poor for occasional wear. |
| Scleral lens | Large GP lens; vaults cornea; for keratoconus, irregular cornea, post-surgical, severe dry eye, graft-versus-host disease (GvHD). ~16–22 mm diameter. |
| Orthokeratology | Overnight wear; temporary corneal reshaping; best for low-moderate myopia; myopia control benefit ~40–60%. |
| Hybrid lens | GP center + soft skirt; combines RGP optics with SCL comfort. SynergEyes, UltraHealth. |
Ref: Efron, Contact Lens Practice, 4th ed. AOA Contact Lens & Anterior Segment guidelines.
Special patient considerations
Presbyopia, astigmatism, keratoconus, dry eye
Prescribing▾
| Presbyopia | Multifocal SCL (Biofinity MF, Acuvue MF, Dailies Total1 MF); monovision (dominant eye distance, non-dom near); or reading glasses over CLs. Trial both — multifocal preferred for active patients. |
| High astigmatism (>2.50D) | Soft toric has limits — consider RGP or scleral. Custom soft toric (Bausch + Lomb, CooperVision) available for higher cylinders. |
| Keratoconus | Mild: soft toric or RGP. Moderate–severe: RGP (Rose K2), scleral (ICD, Onefit), or hybrid. Corneal cross-linking if progressing. |
| Dry eye in CL wearers | Switch to daily disposable; increase Dk; try silicone hydrogel; use PF rewetting drops; reduce wearing time; consider scleral if severe. |
| Post-refractive surgery | Irregular ablation: scleral or RGP. Residual refractive error: standard SCL or RGP depending on irregularity. Dry eye often co-existing — manage aggressively. |
Ref: AAO Refractive Management/Intervention PPP 2022. Global Keratoconus Consensus, Cornea 2015;34:359.
Cranial Nerves — Optometry Review
CN II through VIII with optometric relevance
Cranial nerves quick reference
Function, optometric significance, clinical pearls
Neuro▾
| CN II — Optic | Afferent visual pathway. Tests: VA, CVF, color vision, pupil (RAPD), OCT RNFL. Lesions: optic neuritis, NAION, compression, glaucoma. |
| CN III — Oculomotor | SR, IR, MR, IO + levator + pupil constriction (EWN). Palsy: "down and out" + ptosis ± mydriasis. Pupil-involving = aneurysm until proven otherwise. |
| CN IV — Trochlear | Superior oblique only. Palsy: hypertropia worsened by contralateral gaze + ipsilateral head tilt. Most commonly injured in head trauma. Parks 3-step to identify. |
| CN V — Trigeminal | V1 (ophthalmic): corneal reflex afferent, forehead sensation; V2 (maxillary): cheek, lower lid. Herpes zoster ophthalmicus: V1 distribution. Neurotrophic keratitis: decreased corneal sensation. |
| CN VI — Abducens | Lateral rectus only. Palsy: esotropia worse at distance and in gaze toward the affected side; limited abduction. Most common cause in adults: microvascular (DM/HTN). In children: rule out raised ICP. |
| CN VII — Facial | Orbicularis oculi (efferent blink reflex); Bell's palsy: lagophthalmos → exposure keratopathy. Treat: lubrication, taping at night, moisture chamber. Refer if corneal involvement. |
| CN VIII — Vestibulocochlear | Vestibular branch: affects nystagmus, gaze stability. VOR testing: head impulse test. Acoustic neuroma: may present with unilateral hearing loss + nystagmus. |
Ref: AAO Neuro-Ophthalmology BCSC 2023–24. Walsh & Hoyt's Clinical Neuro-Ophthalmology.
Corneal reflex pathway
Afferent CN V1, efferent CN VII
Neuro▾
- Afferent: Corneal touch → CN V1 (nasociliary branch) → trigeminal sensory nucleus
- Efferent: Bilateral CN VII → orbicularis oculi contraction (direct + consensual blink)
- If afferent defect (CN V): Neither eye blinks when affected cornea touched; both blink when normal cornea touched
- If efferent defect (CN VII): Affected eye doesn't blink regardless of which cornea is stimulated; consensual blink normal in other eye
- Neurotrophic keratitis: decreased/absent corneal sensation; risk of sterile ulceration; use PF lubricants aggressively; refer if epithelial breakdown
Ref: AAO Neuro-Ophthalmology BCSC 2023–24.
Key Considerations for Binocular Vision
Optimizing BV — clinical decision framework
The BV triad — AC/A, phoria, vergence
Foundation of binocular vision analysis
BV▾
| AC/A ratio | Accommodative convergence per diopter of accommodation. Normal 4:1 ± 2. High AC/A → eso at near (CE); Low AC/A → exo at near (CI). Gradient method: phoria change per 1D lens. |
| Phoria | Latent deviation. Norm: ~1Δ exophoria (±2) at distance; up to ~6Δ exophoria at near is typical. Sheard's criterion: compensating vergence (toward the phoria) should be ≥ 2× the phoria magnitude — if not met, the patient is likely symptomatic. |
| Vergence ranges | BI/BO blur-break-recovery. Sheard's criterion: blur point ≥ 2× phoria for comfortable BV. Percival's criterion: less commonly used; working point in middle 1/3 of total vergence range. |
Ref: Scheiman & Wick, Clinical Management of Binocular Vision, 5th ed. 2019.
Treatment hierarchy for BV anomalies
Lenses → prism → vision therapy decision tree
Treatment▾
- Correct refractive error first — uncorrected hyperopia drives accommodative esotropia; myopic correction affects exophoria. Always recheck BV after new Rx.
- Lens modification — added plus at near for CI/AI/CE; minus for divergence excess. Most effective when AC/A is the driver.
- Prism — BI for exophoria; BO for esophoria. Use Sheard or Percival to determine amount. Beware: prism doesn't improve fusional vergence; may cause adaptation.
- Vision therapy — most effective for CI, CE, AI, AF. Office-based > home-based (CITT study). 12–24 sessions typically. Best outcomes in motivated patients.
- Surgery — for large angle strabismus; refer to pediatric ophthalmology or strabismus specialist.
Ref: CITT Study Group, Arch Ophthalmol 2008;126:1336. Scheiman & Wick, 5th ed.
Amblyopia — detection and management
Types, treatment options, critical period
Amblyopia▾
| Refractive | Bilateral (isometropic) or unilateral (anisometropic). Rx first — allow 4–6 months before initiating patching. Anisometropia threshold: >1.50D sphere, >1.00D cyl, >3.00D myopia. |
| Strabismic | Constant unilateral tropia; depth of suppression determines amblyopia depth. Rx + patching/atropine penalization. |
| Deprivation | Ptosis, cataract, corneal opacity — most severe form; treat underlying cause ASAP regardless of age. |
| Patching | 2 hrs/day (moderate amblyopia) to 6 hrs/day (severe) per PEDIG studies. Near activities during patching improve outcomes. |
| Atropine penalization | 1% atropine QSat in fellow eye; equivalent to patching for moderate amblyopia; good for compliance issues. |
| Critical period | Best outcomes before age 7; treatment still possible up to age 17 (PEDIG); amblyopia in adults can improve with sustained treatment. |
Ref: PEDIG amblyopia trials, summarized AAO Amblyopia PPP 2022.
Vertex Distance Conversion
Convert spectacle Rx to contact lens power
Vertex distance formula
When compensation is required and how to calculate
Formula▾
Formula: F_CL = F_spec ÷ (1 − d × F_spec) where d = vertex distance in meters (typically 0.012–0.014 m)
Compensation required when spectacle power ≥ ±4.00 D. Below ±4.00 D, the difference is clinically insignificant (<0.25 D).
Quick reference table (12 mm vertex, rounded to nearest 0.25 D):
| Spectacle Rx | CL Power | Spectacle Rx | CL Power |
| +4.00 | +4.25 | −4.00 | −3.75 |
| +5.00 | +5.25 | −5.00 | −4.75 |
| +6.00 | +6.50 | −6.00 | −5.50 |
| +7.00 | +7.75 | −7.00 | −6.50 |
| +8.00 | +8.75 | −8.00 | −7.25 |
| +9.00 | +10.00 | −9.00 | −8.00 |
| +10.00 | +11.25 | −10.00 | −9.00 |
| +12.00 | +14.00 | −12.00 | −10.50 |
Ref: Brooks & Borish, System for Ophthalmic Dispensing, 3rd ed.
SAM-FAP rule for RGP power adjustment
Steeper Add Minus / Flatter Add Plus
RGP▾
- SAM: Steeper than K → Add Minus to the lens power (over-minused by lacrimal lens)
- FAP: Flatter than K → Add Plus to the lens power (over-plussed by lacrimal lens)
- Rule of thumb: Every 0.05 mm change in BC = approximately 0.25 D change in lacrimal lens power
- Example: Spectacle Rx –3.00; K = 44.00 D; BC fitted at 7.60 mm (44.50 D) → steeper by 0.50 D → add –0.50 D → CL power = –3.50 D (then apply vertex if needed)
Ref: Bennett & Henry, Clinical Manual of Contact Lenses, 4th ed.
Billing & Coding for ODs
E&M codes, eye codes, medical vs routine, key modifiers
Eye codes vs E&M codes — when to use each
92000 series vs 99000 series
Coding▾
| Eye exam codes (92XXX) | For routine/preventive eye exams (refractive, contact lens). Used with vision insurance. Cannot be billed same day as E&M for same diagnosis. |
| 92002 | New patient — intermediate eye exam (no dilation required) |
| 92004 | New patient — comprehensive eye exam (includes dilation) |
| 92012 | Established patient — intermediate |
| 92014 | Established patient — comprehensive (includes dilation) |
| E&M codes (99XXX) | For medical eye conditions. Used with medical insurance (Medicare, medical plans). Based on medical decision making (MDM) or time. |
| 99213/99203 | Low MDM — e.g., simple chronic condition like mild glaucoma suspect, stable dry eye |
| 99214/99204 | Moderate MDM — e.g., new diagnosis requiring Rx management, uncontrolled DM with DR |
| 99215/99205 | High MDM — e.g., complex new problem, acute vision loss, multiple chronic conditions |
Ref: AMA CPT 2024. AOA coding resources. CMS E/M documentation guidelines 2021.
Key diagnostic test codes
OCT, VF, fundus photography, corneal topography
Coding▾
| 92133 | OCT — optic nerve / RNFL (glaucoma) |
| 92134 | OCT — posterior segment / macula (retina) |
| 92132 | Scanning computerized ophthalmic diagnostic imaging, anterior segment (cornea, anterior chamber) |
| 92083 | Visual field exam — threshold (Humphrey, Octopus) |
| 92082 | Visual field — suprathreshold (confrontation fields do not bill) |
| 92250 | Fundus photography with interpretation and report |
| 92025 | Corneal topography |
| 92285 | External ocular photography (anterior segment) |
| 76514 | Pachymetry (corneal thickness) |
| 92020 | Gonioscopy |
| 92081 | VF — limited (Amsler grid does not bill separately) |
Ref: AMA CPT 2024. CMS National Physician Fee Schedule.
Medical decision making (MDM) — key elements
How to document to support your E&M level
Coding▾
MDM has 3 components — need 2 of 3 to meet level:
| Number & complexity of problems | Minimal (1 self-limited) → Low (2 self-limited or 1 stable chronic) → Moderate (1 uncontrolled chronic / new problem) → High (severe threat to life/function) |
| Amount of data reviewed | Minimal → Limited (review 1 source) → Moderate (review external records OR order tests OR discuss with another provider) → Extensive (2+ of above) |
| Risk of complications | Minimal → Low (OTC drugs) → Moderate (Rx drugs, minor procedure) → High (drug therapy requiring intensive monitoring, major surgery) |
Document your MDM clearly in your exam note. The note must support the code billed. "If it's not documented, it didn't happen." Use a structured template for consistency.
Ref: AMA CPT 2024 E/M guidelines (2021 revision). CMS documentation guidelines.
Modifiers & common billing pitfalls
-25, -59, ABN, split billing
Billing▾
| Modifier -25 | Significant, separately identifiable E&M service on the same day as a procedure. Required when billing an E/M service (99XXX) on the same day as a procedure. The -25 modifier goes on the E/M code to indicate it is a significant, separately identifiable service. Common example: billing 99214 + 92133 on the same day. |
| Modifier -59 | Distinct procedural service — indicates a procedure is separate/distinct from another on the same day. Use when two procedures might otherwise be bundled. |
| ABN (Advance Beneficiary Notice) | Required for Medicare patients when billing a service that may be denied. Patient acknowledges they may be responsible for payment. Must be signed BEFORE the service. |
| Routine vs medical billing | Never bill the same service to both vision and medical insurance. Document clearly whether visit is medical or routine. Split billing (routine refraction + medical E&M) is acceptable when genuinely separate services. |
| Refraction (92015) | Not covered by Medicare; always patient responsibility or vision insurance. Can charge privately. Document as routine service. |
⚠ Upcoding (billing a higher level than documented) and unbundling are the most common OD audit triggers. Regular coding audits and documentation review recommended.
Ref: AMA CPT 2024. CMS Global Surgery & Modifier guidance. OIG compliance guidance.
Practice Revenue Guide
Budgeting, benchmarks, and revenue optimization for OD practices
Practice benchmarks — know your numbers
Revenue per exam, capture rate, key metrics
Benchmarks▾
| Revenue per exam | Industry average: $250–$350/comprehensive exam. High-performing practices: $400–$500+. Includes professional + optical. |
| Optical capture rate | % of Rx patients who purchase glasses in your office. Average: 55–65%. Target: >70%. |
| CL conversion rate | % of patients fit in CLs. Average: 20–25% of patient base. CL revenue per patient: $200–$400/yr (fit fee + supplies). |
| Exams per day | Solo OD: 14–18 exams/day typical. With support staff: 20–24 achievable. High volume: 30+ with efficient protocols. |
| Chair cost | Cost to open doors for one exam slot: typically $75–$120. Know your break-even number. |
| Net collection rate | Amount actually collected vs amount billed. Target: >95%. Below 90% = billing process problem. |
| Annual revenue benchmarks | Solo OD private practice: $600K–$1.2M typical range. Corporate: $400K–$700K gross. Medical model/specialty: $1.5M+. |
Ref: MBA/practice-management benchmarks; figures are illustrative industry ranges, verify locally.
Revenue per category — where the money comes from
Professional fees, optical, CLs, medical, ancillary
Revenue▾
| Professional fees | E&M + eye codes + diagnostic testing. Anchor revenue — roughly 40–50% of total in mixed practice. |
| Optical/spectacles | Highest margin product in practice. Gross margin on frames: 50–70%. Lens gross margin: 60–80%. Target: optical revenue = 40–50% of total. |
| Contact lenses | Lower margin (~20–30% on materials) but high volume and annual recall driver. Fit fees and annual supply sales. |
| Medical/specialty services | Dry eye procedures (LipiFlow $800–1,200), myopia management, low vision, vision therapy — highest revenue per hour. Often under-developed opportunity. |
| Ancillary revenue | Nutraceuticals, supplements (AREDS2, omega-3), sunglasses, accessories. Low effort, high margin. Add to checkout workflow. |
Ref: Practice-management estimates; illustrative ranges only, verify with your own data.
Increasing revenue — actionable levers
Quick wins and longer-term strategies
Strategy▾
Quick wins (implement this month):
- Audit recall system — every patient should have a recall reminder. 1% improvement in show rate = significant revenue.
- Ensure every Rx patient is escorted to optical — capture rate drops sharply without warm handoff.
- Bill diagnostics appropriately — OCT, VF, fundus photos often under-billed or forgotten.
- Offer annual CL supply with discount — improves capture, patient loyalty, and cash flow.
- Add ancillary sales to checkout (nutraceuticals, plano sun, blue light lenses).
Longer-term strategies:
- Build a medical optometry model — glaucoma co-management, DED procedures, myopia management = higher revenue per hour than routine exams.
- Add vision therapy — high per-hour revenue; differentiates practice; strong referral network builder.
- Optimize fee schedule annually — compare to local UCR (usual, customary, reasonable) fees.
- Track and reduce no-shows — automated reminders, deposit for new patient slots.
- Evaluate insurance mix — lowest-paying plans may be worth dropping if they fill slots that block higher-paying patients.
Ref: General practice-management guidance; not from a single peer-reviewed source.
Simple practice budget framework
Expense ratios and overhead targets
Budgeting▾
Target expense ratios as % of gross revenue (private practice):
| Staff/payroll | 25–30% (including OD salary in solo) |
| Optical COGS | 18–22% (frames + lenses cost) |
| CL COGS | 8–12% |
| Rent/occupancy | 7–10% |
| Marketing | 3–5% |
| Equipment/technology | 3–5% |
| Professional fees (billing, legal, accounting) | 2–4% |
| Miscellaneous/supplies | 2–3% |
| Target overhead | 60–70% of gross revenue |
| Net OD income | 30–40% of gross revenue |
If overhead exceeds 70%, prioritize: reduce COGS (optical pricing strategy), review staffing ratios, and increase revenue per exam before cutting marketing.
Ref: Illustrative practice-management expense ratios; verify against your own financials.
Pupils
Anisocoria, RAPD, Horner's, tonic pupil
The 4 anisocoria questions
First steps in any pupil asymmetry
Workup▾
- Is the anisocoria equal in bright and dim light?
- Are there motility problems?
- Do pupils react to light and near?
- Is it physiologic (asymmetry <1mm, no other signs)?
Afferent (RAPD)
Swinging flashlight: affected eye dilates when light swings to it → optic nerve or severe retinal disease.
Causes of RAPD: optic neuritis, extensive retinal disease, optic tract/prechiasmal lesion, rim pallor, VF defect, NLP eye. "Can't get an APD at or beyond the LGN."
5 reasons for light-near dissociation:
- Tectal (dorsal midbrain syndrome)
- Blind Eye (NLP — Amaurotic pupil)
- Adie's tonic pupil
- Argyll Robertson
- Aberrant regeneration of CN III
Ref: Kardon, in Walsh & Hoyt's Clinical Neuro-Ophthalmology. AAO Neuro BCSC 2023–24.
Horner's syndrome
1st, 2nd & 3rd order localization
Neuro▾
Classic triad: miosis + ptosis + anhidrosis (ipsilateral)
| Cocaine 4% | Confirms Horner's — no dilation in any order |
| Hydroxyamphetamine | Dilates in 1st/2nd order; NO dilation in 3rd order (postganglionic) |
| Apraclonidine 0.5% | Reversal of anisocoria confirms Horner's (denervation hypersensitivity) |
1st Order (central):
- Wallenberg (lateral medullary syndrome)
- Spinal cord lesion
2nd Order (preganglionic):
- Lung apex tumor (Pancoast)
- Brachial plexus injury
- Neck or shoulder injury
3rd Order (postganglionic):
- Cluster headache
- Trauma/carotid dissection
- Cavernous sinus lesion
⚠ New Horner's + neck pain → carotid dissection until proven otherwise. Urgent vascular imaging.
Ref: Kanagalingam & Miller, Eye 2015;29:291. AAO Neuro-Ophthalmology BCSC 2023–24.
Adie's tonic pupil & others
Postganglionic denervation, pharmacologic, CN III
Neuro▾
| Adie's | Large, poorly reactive; near-light dissociation; sectoral iris movement; young females; 0.1% pilocarpine → constriction (denervation hypersensitivity) |
| Argyll Robertson | Small, irregular; constrict to near NOT light; bilateral; neurosyphilis |
| Pharmacologic mydriasis | No response to 1% pilocarpine; anticholinergics (atropine, scopolamine patch) |
| CN III palsy | "Down and out" + ptosis; pupil-involving = posterior communicating aneurysm until proven otherwise. Urgent MRI/MRA. |
⚠ Pupil-involving CN III palsy is a neurosurgical emergency — call immediately.
Ref: Thompson, Adie's syndrome, Trans Am Ophthalmol Soc 1977. AAO Neuro BCSC 2023–24.
Headache
Primary types, emergency red flags, ocular causes
Primary headache types
Tension, migraine, cluster
Primary▾
1. Tension
- Usually bilateral; band/pressure over temples and occipital region; no nausea
2. Cluster
- Periorbital, unilateral; autonomic features; lasts 15–180 min; photophobia
3. Migraine
- Unilateral; pulsating; with/without aura; nausea; photophobia; 4–72 hrs
- Visual aura in 30–50% — scintillating scotoma, fortification spectra
Workup: r/o ocular disease — EOMs, pupils, CVF, refraction. Order VF for new aura to r/o occipital lesions. Caused by cortical spreading depression (CSD).
Ref: ICHD-3, Cephalalgia 2018;38:1. AAO Neuro-Ophthalmology BCSC 2023–24.
Emergency secondary headaches
Must-not-miss diagnoses
Emergency▾
- Giant cell arteritis (≥50 yrs) — temporal HA + scalp tenderness + jaw claudication. Same-day ESR/CRP. Start steroids before biopsy if vision threatened.
- Papilledema / raised ICP — transient visual obscurations, disc edema. MRI to r/o mass & venous sinus thrombosis.
- Pituitary apoplexy — sudden HA, vision loss, motility problems, ptosis, hormonal dysfunction
- Aneurysm (PCoA) — thunderclap onset; CN III palsy with blown pupil
- Carotid artery dissection — neck pain + Horner's; urgent MRA
- Acute angle closure — unilateral HA + red eye + halos + nausea; IOP often >40 mmHg
⚠ "Worst HA of life", new HA + fever/stiff neck, positional HA worse supine, papilledema, APD, or new VF loss → refer same day.
Ref: ICHD-3, Cephalalgia 2018. GCA: ACR/EULAR criteria, Ann Rheum Dis 2022.
Ocular causes of headache
Rule out at every headache presentation
Ocular DDx▾
| Refractive error | Frontal/brow ache with near work; worse as day progresses; resolves with correction |
| Convergence insufficiency | Bifrontal HA with reading; NPC >10 cm; high exophoria at near |
| Accommodative dysfunction | End-of-day HA; especially under-corrected hyperopes or early presbyopes |
| Dry eye | End-of-day brow ache; often misattributed to tension HA |
| Acute angle closure | Severe unilateral HA + red eye + halos + nausea; fixed mid-dilated pupil; IOP >40 mmHg |
| GCA ≥50 yrs | Temporal HA + scalp tenderness + jaw claudication; AION risk |
Ref: AAO Neuro-Ophthalmology BCSC 2023–24.
Diplopia
Monocular vs binocular, horizontal & vertical workup, CN syndromes
Initial workup
4 key questions + history
Workup▾
- Does it go away when you cover either eye? (monocular vs binocular)
- Is it worse at distance or near?
- Worse in which direction of gaze?
- Is it up/down or side to side?
Key history: DM, HTN, cancer, thyroid, MS, prior orbital surgery, strabismus, amblyopia
⚠ New vertical diplopia, ptosis + diplopia, pupil-involving CN III, or diplopia + headache → urgent same-day referral/imaging.
Ref: Danchaivijitr & Kennard, J Neurol Neurosurg Psychiatry 2004;75:iv24 (diplopia approach).
Horizontal diplopia DDx
Etiology and distinguishing features
Horizontal▾
| CN VI palsy | Esotropia at distance; limited abduction; microvascular (DM/HTN) vs elevated ICP |
| Thyroid eye disease | Lid retraction, proptosis, restrictive; IR most commonly affected; worse upgaze |
| Myasthenia gravis | Variable/fatigable; worse end of day; Cogan lid twitch; ice pack test positive |
| INO | Adduction deficit + contralateral abduction nystagmus; MLF lesion; stroke or MS |
| Decompensated phoria | Gradual onset; prior strabismus history; recent illness/stress |
Ref: AAO Neuro-Ophthalmology BCSC 2023–24. Walsh & Hoyt's.
CN III — six localizing syndromes
Brainstem through orbit
CN III▾
- Brainstem — Benedikt, Weber; look for other CN involvement, cerebellar signs, nystagmus
- Subarachnoid space — PCoA aneurysm; pupil-involving → emergent MRI/MRA
- Posterior communicating artery — pupil-blown = aneurysm until proven otherwise
- Cavernous sinus — CN 3,4,5 V1, Horner's; parasellar mass
- Orbital — co-involvement of all orbital structures
- Microvascular (DM/HTN) — typically pupil-sparing; improves in 3–6 months
| Complete CN III palsy | Eye "down and out"; ptosis; no elevation, depression, or adduction |
| Pupil blown | Aneurysm until proven otherwise — emergent imaging |
| Pupil sparing | Likely microvascular; monitor; watch for aberrant regeneration |
Ref: AAO Neuro-Ophthalmology BCSC 2023–24. Walsh & Hoyt's Clinical Neuro-Ophthalmology.
CN IV & EOM actions reference
Trochlear nerve, bilateral palsy, H-pattern
CN IV▾
- Only CN that fully decussates dorsally — right nucleus → left SO palsy
- Most common cause: trauma (dorsal midbrain impact)
- Bilateral CN IV palsy: reversing hypertropia on alternating cover test, large excyclotorsion, V-pattern eso
EOM actions (H-pattern):
| SR/IR | Elevate/depress in abduction (CN III) |
| LR | Abducts (CN VI) |
| MR | Adducts (CN III) |
| SO | Depresses in adduction; intorts (CN IV) |
| IO | Elevates in adduction; extorts (CN III) |
See Parks 3-Step tab for full calculator.
Ref: von Noorden & Campos, Binocular Vision and Ocular Motility, 6th ed.
Nystagmus
Classification, peripheral vs central, specific acquired forms
Classifying nystagmus
Jerk vs pendular, congenital vs acquired
Classification▾
| Direction | Jerk (fast/slow phase) or pendular |
| Conjugate? | Both eyes same vs. dissociated |
| Plane | Horizontal, vertical, torsional, or mixed |
Congenital:
- Null point present; dampens with convergence; worsens with Frenzel goggles
- Horizontal in primary gaze; usually benign — MRI if no null point or worsening
Acquired:
- No null point; does not dampen with convergence; often associated with CNS pathology
Ref: CEMAS Working Group classification, NEI 2001. Walsh & Hoyt's.
Peripheral vs central nystagmus
Key distinguishing features
Localization▾
| Feature | Peripheral | Central |
| Direction | Fixed (horizontal) | Direction-changing or vertical |
| Fixation effect | Suppressed by fixation | NOT suppressed |
| Fast phase | Away from lesion (toward good ear) | Gaze-directed |
| Vertigo | Often severe, episodic | Usually mild or absent |
| Associated Sx | Hearing loss, tinnitus | Other neuro signs |
⚠ Direction-changing nystagmus or vertical nystagmus = central until proven otherwise. MRI brain.
Ref: Walsh & Hoyt's Clinical Neuro-Ophthalmology. AAO Neuro BCSC 2023–24.
Specific acquired types
Upbeat, downbeat, see-saw, periodic alternating
Acquired▾
| Upbeat | Cervicomedullary junction or dorsal vermis; DDx: MS, tumor, Wernicke's |
| Downbeat | Cervicomedullary junction; DDx: Arnold-Chiari (check for disc edema from 4th ventricle compression), MS, tumor |
| See-saw | One eye rises & intorts; other falls & extorts; associated with bitemporal hemianopia; localizes to parasellar/midbrain |
| Periodic alternating (PAN) | Direction reverses every ~90 sec; cervicomedullary junction or cerebellar flocculus; DDx: MS, tumor, phenytoin |
| Gaze-evoked | Beats in direction of gaze; returns to midline at rest; medications (anticonvulsants, alcohol) or cerebellar disease |
Don't confuse PAN with normal physiologic end-gaze nystagmus, which only occurs at extreme lateral gaze (>50°).
Ref: Leigh & Zee, The Neurology of Eye Movements, 5th ed.
Visual Fields
Defect localization by anatomy and DDx
Visual field defect diagrams
Classic patterns with localization and DDx
Diagrams▾
Monocular loss (OS)
Left optic nerve / retina
Central scotoma
Optic neuritis, macular disease
Enlarged blind spot (OD)
Disc edema, drusen, coloboma
Arcuate scotoma (OD)
Glaucoma, NAION
Superior altitudinal (OD)
NAION, BRVO, retinal artery occlusion
Bitemporal hemianopia
Chiasm — pituitary adenoma, craniopharyngioma
Right homonymous hemianopia
Left post-chiasmal lesion
Right HH with macular sparing
Occipital cortex — PCA occlusion
Right superior quadrantanopia
Temporal lobe — "pie in the sky"
Right inferior quadrantanopia
Parietal lobe — "pie on the floor"
Left homonymous hemianopia
Right post-chiasmal lesion
Constricted peripheral field
RP, glaucoma, chronic papilledema
⬜ White = intact field ⬛ Black = field loss Left = OS Right = OD (patient's perspective — standard optometric convention)
Ref: AAO Neuro-Ophthalmology BCSC 2023–24. Walsh & Hoyt's.
Pre-chiasmal defects
Monocular — retina or optic nerve
Pre-chiasmal▾
| Monocular total loss | Optic nerve: ischemic, compressive, inflammatory (optic neuritis) |
| Central scotoma | Optic neuritis, macular disease, toxic optic neuropathy |
| Cecocentral scotoma | Toxic/nutritional optic neuropathy (B12, ethambutol, methanol) |
| Arcuate scotoma | Glaucoma, NAION, tilted disc |
| Altitudinal defect | NAION, BRVO, retinal artery occlusion |
| Enlarged blind spot | Disc edema, coloboma, drusen, staphyloma, high myopia |
| Constricting peripheral | RP, chronic papilledema, glaucoma, post-PRP, toxic neuropathy |
Ref: AAO Neuro-Ophthalmology BCSC 2023–24.
Chiasmal & post-chiasmal defects
Bitemporal, homonymous, quadrantanopia
Chiasmal▾
| Bitemporal hemianopia | Chiasm (decussating fibers); DDx: pituitary adenoma, craniopharyngioma, meningioma, hypothalamic tumor, tilted discs |
| Nasal hemianopia (monocular) | Lateral chiasm compression — aneurysm of ACA, pituitary adenoma |
| Homonymous hemianopia | Post-chiasmal; less congruent = more anterior; more congruent = more posterior (occipital) |
| Superior homonymous quadrantanopia | Temporal lobe ("pie in the sky"); DDx: temporal lobe tumor |
| Inferior homonymous quadrantanopia | Parietal lobe ("pie on the floor") |
| HH with macular sparing | Occipital cortex — dual blood supply (MCA + PCA); DDx: PCA occlusion |
| Bilateral field loss | Glaucoma, RP, bilateral ICA aneurysm, bilateral occipital infarction |
Most lesions at the chiasm are tumors. Most lesions beyond the chiasm are vascular.
Ref: AAO Neuro-Ophthalmology BCSC 2023–24. Walsh & Hoyt's.
VF interpretation pearls
Congruence rules, macular sparing, testing tips
Tips▾
- Anterior to nodal point: superior VF defect = inferior pathology on retina
- Posterior to nodal point: inferior VF defect = superior pathology
- Incorrect Rx causes overall constriction — always verify correction before perimetry
- Reliability indices matter: fixation losses (FL) >20%, false positives (FP) >15%, false negatives (FN) >33% each indicate an unreliable field
- Pattern deviation preferred over total deviation when diffuse loss is present
- GHT (Glaucoma Hemifield Test) outside normal limits = significant asymmetry
Ref: Heijl et al., Humphrey Field Analyzer Primer, 5th ed. AAO Glaucoma BCSC 2023–24.
Glaucoma
Assessment framework, IOP medications, angle closure emergency
Glaucoma evaluation framework
Disc, IOP, CCT, angle, RNFL
Glaucoma▾
| Target IOP | 25–30% reduction from baseline; <15 mmHg if advanced damage |
| C/D ratio concerns | Asymmetry ≥0.2; vertical elongation; notching; disc hemorrhage; RNFL defects |
| CCT | Thin (<520 μm) = independent risk factor; GAT overestimates IOP with thick corneas |
| Gonioscopy | Always grade before dilation; Shaffer grade <2 = narrow/occludable |
| OCT RNFL | Focal thinning often precedes VF loss by years; track serially |
| NTG workup | Systemic hypotension, sleep apnea, vasospasm; nocturnal dips; 24-hr IOP curve |
Ref: AAO Primary Open-Angle Glaucoma PPP 2020. Weinreb et al., JAMA 2014;311:1901.
IOP-lowering medications
Mechanism, expected reduction, cost
Glaucoma Rx▾
| Latanoprost 0.005% (Xalatan) | Prostaglandin; QHS; ~25–33% ↓; ~$15–30 generic |
| Bimatoprost 0.03% (Lumigan) | Prostamide; QHS; ~27–33% ↓; ~$20–40 generic |
| Timolol 0.5% | Beta-blocker; BID; ~20–25% ↓; ~$10–20 generic |
| Cosopt (dorzolamide/timolol) | CAI + BB combo; BID; ~25–30% ↓; ~$30–60 generic |
| Brimonidine 0.2% (Alphagan) | Alpha-2 agonist; BID-TID; ~20% ↓; ~$15–35 |
| Netarsudil 0.02% (Rhopressa) | Rho-kinase inhibitor; QHS; ~20% ↓; ~$200 brand |
⚠ Timolol: avoid in asthma/COPD/bradycardia. Prostaglandins: counsel on iris pigmentation, lash growth, fat atrophy.
Ref: AAO POAG PPP 2020. European Glaucoma Society Guidelines, 5th ed. 2020.
Acute angle closure — emergency management
Recognition & immediate steps
Emergency▾
| Presentation | Severe HA, nausea/vomiting, halos, blurred vision, fixed mid-dilated pupil, corneal edema; IOP >40–60 mmHg |
| Immediate Rx | Timolol 0.5% + brimonidine 0.2% + dorzolamide 2% + acetazolamide 500 mg PO or IV; pilocarpine 1–2% after IOP begins to drop |
| Definitive Tx | Laser peripheral iridotomy (LPI) OU — treat fellow eye prophylactically |
⚠ IOP >40 mmHg with symptoms = ophthalmic emergency. Refer immediately.
Ref: AAO Primary Angle Closure PPP 2020. Sng et al., Asia Pac J Ophthalmol 2018.
Binocular Vision Workup
Distance phoria, vergences, von Graefe, FCC, MEM
Distance lateral phoria — von Graefe
Step-by-step technique
Technique▾
Setup: Distance correction & PD in phoropter; OD: 12 BI (measuring); OS: 6 BU (dissociating)
- Isolate one letter — one line larger than best VA
- Patient sees two images: one up and to the right
- "Tell me when the two targets line up like buttons"
- Reduce BI prism until alignment, then overshoot
- Bring back; average two values if within 3Δ; if not, repeat
| Expected | N: 3Δ (±3) for presbyopes; Ortho for younger patients |
| AC/A ratio | Repeat through +1.00D or –1.00D. Expected 4:1 ± 2. |
Ref: Scheiman & Wick, Clinical Management of Binocular Vision, 5th ed.
Distance horizontal vergences (BI & BO)
Break and recovery measurement
Technique▾
- Increase prism slowly — note blur point, break point, recovery point
- Detect suppression: OD → target drifts right; OS → target drifts left
- If no blur point with BO, common — record as "x/break/recovery"
- BI and BO on same isolated letter, larger than best VA
| Expected (Sheedy & Saladin) | BI: 7/15/12 BO: 15/28/20 |
Ref: Sheedy & Saladin, Am J Optom Physiol Opt 1978;55:670. Scheiman & Wick, 5th ed.
FCC & MEM
Functional accommodative tests at near
Testing▾
FCC (Fused Cross-Cylinder):
- FCC card (grid) at 40 cm in dim illumination; red dots at 90°
- Ask: "Which lines sharper — going up/down or side to side?"
- Add (+) OU until lines appear equal
Expected: +0.25 to +0.50 D
MEM (Monocular Estimate Method):
- Attach MEM card to retinoscope; patient wears habitual Rx at working distance
- Quickly neutralize reflex with trial lens — don't let patient accommodate to the lens
- Record power needed OU
Expected: +0.25 to +0.50 D (lag of accommodation)
Ref: Scheiman & Wick, Clinical Management of Binocular Vision, 5th ed.
Vergence Anomalies
CI, CE, basic exo/eso, divergence anomalies
Convergence insufficiency (CI)
Most common binocular vision disorder
Vergence▾
Symptoms (near): Headaches; blurred or double vision; eyestrain; movement of print; pulling sensation
Signs: Low AC/A; high exo at near > distance; ortho/suppresses at distance; receded NPC (improves with +); low NRA; high MEM; poor BO near recovery; poor facility with (+) OU
| Primary Tx | Vision therapy (VT) — office-based preferred |
| Secondary Tx | BO prism at near; beware prism adaptation |
| Pseudo-CI | Same symptoms/signs; NPC improves with (+) → treat underlying AI first |
Ref: CITT Study Group, Arch Ophthalmol 2008;126:1336.
Convergence excess (CE)
High AC/A esophoria at near
Vergence▾
Symptoms (near): Headache; blurred vision; eyestrain; diplopia at near
Signs: High AC/A; high eso at near > distance; ortho at distance; high MEM & FCC; low NRA; poor facility with (+) OD, OS, OU; normal-high amplitude
| Primary Tx | Added (+) lenses at near |
| Secondary Tx | VT |
Ref: Scheiman & Wick, Clinical Management of Binocular Vision, 5th ed.
Basic exo & eso, divergence anomalies
Equal deviation & distance-predominant conditions
Vergence▾
| Basic Exophoria | Equal exo distance & near; low MEM; poor BO both distances; facility worse with (+). Tx: VT; BO prism secondary (per Sheard's criterion). |
| Basic Esophoria | Equal eso distance & near; often with hyperopia; poor BI; facility worse with (–). Tx: VT; BI prism or Rx update. |
| Divergence insufficiency | Higher eso at distance than near; diplopia at distance; halos in car/train. Tx: BI prism primary. |
| Divergence excess | Higher exo at distance than near; high AC/A; may close one eye in bright light. Tx: minus lenses primary. |
Ref: Scheiman & Wick, Clinical Management of Binocular Vision, 5th ed.
Quick reference — vergence anomaly summary
AC/A, phorias, and primary treatment
Reference▾
| Condition | AC/A | Distance | Near | Primary Tx |
| CI | Low | Ortho | High exo | VT |
| CE | High | Ortho | High eso | Add (+) |
| Basic exo | Normal | Exo | Equal exo | VT / prism |
| Basic eso | Normal | Eso | Equal eso | VT / prism |
| Div. insuff. | Low | High eso | Ortho | BI prism |
| Div. excess | High | High exo | Ortho | Minus lenses |
Ref: Scheiman & Wick, Clinical Management of Binocular Vision, 5th ed.
Accommodative Anomalies
Insufficiency, infacility, excess, spasm
Accommodative insufficiency (AI)
Low amplitude, poor sustaining
Accommodation▾
Symptoms: Blurry near vision; eyestrain; print movement; difficulty reading
Signs: Low amplitude (below Hofstetter minimum); low PRA; high MEM & FCC; reduced facility with (–); eso at near or XT
| Primary Tx | Added (+) at near |
| Secondary Tx | VT (accommodative facility training) |
Hofstetter's: Minimum = 15 – 0.25(age); Expected = 18.5 – 0.30(age)
Ref: Scheiman & Wick, 5th ed. Hofstetter, Am J Optom 1947 (amplitude norms).
Accommodative infacility (AF)
Slow or inconsistent focusing
Accommodation▾
Symptoms: Blurry vision after near work; headaches; difficulty switching focus; light sensitivity
Signs: Normal-high amplitude; low NRA and PRA; low MEM & FCC; poor facility with both (+) and (–) OD, OS, OU
| Primary Tx | VT (accommodative facility training) |
Ref: Scheiman & Wick, Clinical Management of Binocular Vision, 5th ed.
Accommodative excess & spasm
Over-accommodation, pseudomyopia
Accommodation▾
Accommodative Excess (AE):
Sx: Blurry distance vision after near work; headaches; eyestrain
Signs: High MEM & FCC; low PRA; poor facility with (+); eso tendency at near; high amplitude
Tx: VT
Accommodative Spasm:
Sx: Pseudomyopia; intermittent blurry distance; diplopia; miotic pupils; rare
Signs: Miotic pupils; variable refraction; triad: over-accommodation + convergence + miosis; may be psychogenic or organic
Tx: Cycloplegic refraction essential; VT; cycloplegic drops if severe; rule out drug cause (pilocarpine, organophosphate) and organic cause (dorsal midbrain tumor)
Ref: Scheiman & Wick, 5th ed. AAO Pediatric Ophthalmology BCSC 2023–24.
Dry Eye
DEWS II classification, testing, treatment ladder
Dry eye evaluation — DEWS II
Symptom screen, TBUT, staining, Schirmer, MGD
Assessment▾
Symptom screen: OSDI or DEQ-5. OSDI ≥23 = moderate-severe.
| TBUT | <10 sec non-invasive; <5 sec fluorescein → abnormal |
| Staining | Oxford scale (corneal 0–5); Van Bijsterveld (conjunctival) |
| Schirmer's I | <5 mm/5 min = severe aqueous deficiency |
| Phenol red thread | <10 mm = aqueous deficiency; less reflex tearing than Schirmer |
| MGD grading | Meiboscore 0–3 per lid; assess gland expressibility and secretion quality |
Classify first: Aqueous deficient (Sjögren's vs. non-Sjögren's) vs. Evaporative (MGD most common). Classification drives treatment.
Ref: DEWS II Diagnostic Methodology, Wolffsohn et al., Ocul Surf 2017;15:539.
Treatment ladder
Step-up approach by severity
Treatment▾
Step 1 — Mild:
- Patient education; omega-3 supplementation
- Preserved artificial tears QID or PRN
- Eyelid hygiene; warm compresses for MGD
Step 2 — Moderate:
- Non-preserved artificial tears
- Cyclosporine 0.05% (Restasis) BID or lifitegrast 5% (Xiidra) BID
- LipiFlow or thermal pulsation for MGD
- Punctal plugs (lower first)
- Topical azithromycin for meibomian gland disease
Step 3 — Severe:
- Autologous serum tears
- Scleral lenses
- Short-term topical steroids (loteprednol BID)
- Amniotic membrane
Step 4 — Very severe:
- Systemic anti-inflammatory agents
- Surgical punctal occlusion
- Tarsorrhaphy
Ref: DEWS II Management & Therapy, Jones et al., Ocul Surf 2017;15:575.
Contact Lens Fitting
RGP fitting, BC selection, residual astigmatism, toric designs
RGP — spherical BC selection
Fitting philosophy & power compensation
| Large diameters (10.0) | Kavg – 1.500 |
| Small diameters (9.6) | Kavg – 0.500 |
| Plano | –0.18 mm |
| Minus lenses | Subtract 0.01 mm per diopter; e.g. –3.00 D: 3.00 × 0.01 = 0.03 mm |
| Plus lenses | +1.00 D: add 0.01 mm to BC (same rule as minus; steepen for plus) |
| Secondary curves | PCr = BCr + 1.5 mm; SCr = BCr + 1.5 mm |
Conversion formulas:
| D = 337.5 / r(mm) | Convert radius to power |
| +0.05 mm = –0.250 D | Approximation (flatter BC = more minus power in TL) |
Vertex distance power compensation:
| 4.00–5.87 D | Add +0.25 |
| 6.00–7.87 D | Add +0.50 |
| 8.00–9.87 D | Add +0.75 |
| For minus lenses the CL is less minus; for plus lenses the CL is more plus. Magnitudes above; sign follows the lens. | |
Use SAM-FAP to determine CLP change when BC is changed.
Lacrimal lens & residual astigmatism
What the tear layer corrects
| Lacrimal lens | LL = BC – K |
| Residual astigmatism | RA = Spectacle Rx cyl – Keratometric cyl (approximate) |
If RA <0.75 D → spherical RGP works well. If RA ≥0.75 D → consider front surface toric or soft toric.
RGP toric designs — design selection guide
Thin-flex, BST, SPE bitoric, CPE bitoric, FT toric
| Design | Corneal cyl | RA (residual astigmatism) |
| Spherical RGP | ≥1.00 D | ≤0.75 D |
| Back surface toric (BST) | ≥2.00 D | ≤0.75 D |
| SPE bitoric | ≥2.00 D | ≤0.75 D |
| CPE bitoric | ≥2.00 D | ≥0.75 D |
| Front surface toric (FT) | <2.00 D | ≥0.75 D |
BST: Back surface toric; front spherical. Good for corneal cyl with minimal RA.
SPE bitoric: Both surfaces toric; equal power effect in all meridians — appears spherical to patient. For high corneal cyl with minimal RA.
CPE bitoric: Both surfaces toric; corrects both corneal and residual astigmatism.
Lens Material
Material comparison & design strategies for thinner, lighter lenses
Lens material comparison
Index, Abbe value, properties
| Material | Index | Abbe Value | Notes |
| Crown Glass | 1.523 | 58 | Reference standard |
| CR-39 | 1.498 | 58 | Duller sound; most optical clarity |
| Trivex | 1.54 | 43–45 | Impact resistant; lighter than CR-39 |
| Polycarbonate | 1.586 | 30–31 | Highest impact resistance; higher ring sound; most chromatic aberration |
| High index 1.60 | 1.60 | ~36 | Thinner; moderate aberration |
| High index 1.67 | 1.67 | ~32 | Very thin; more aberration |
| High index 1.74 | 1.74 | ~33 | Thinnest; most aberration |
Higher Abbe value = less chromatic aberration. CR-39 and glass have the best optical clarity. Polycarbonate has the lowest Abbe value but best impact resistance — ideal for children and safety eyewear.
Design strategies for thinner, lighter lenses
6 approaches to optimize lens design
- Higher index material
- Minimal decentration
- Rounder frame shape
- Aspheric lens design
- Thinner center
- Smaller frame (smaller ED)
Prism Formulas
Prism formulas, Prentice rule, decentration & blank size
Prism formulas & blank size
Prentice rule, decentration, minimum blank
| Prentice Rule | Δ = (lens power in D) × (decentration in cm) |
| Decentration | Dec(mm) = Δ ÷ lens power |
| Minimum blank size | = ED + 2(decentration per eye) |
Can split prism between both eyes for cosmetic reasons. BI prism for esophoria; BO prism for exophoria.
Power in any meridian (oblique):
| Angle from axis | Difference | % cyl added to sph |
| 30° / 150° | 25 | 50% |
| 45° / 135° | 50 | 75% |
| 60° / 120° | 75 | 100% (full cyl) |
⚕ Clinical reference only. Always verify drug dosages with current prescribing information, confirm ICD-10 codes with your billing department, and apply clinical judgment. Drug and lens prices are approximate retail figures as of April 2026.