Eye in Numbers

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Article initiated by:

Joobin Khadamy, MD, FEBO

All contributors:

Hoon Jung, MD, Joobin Khadamy, MD, FEBO, S. Grace Prakalapakorn, MD, MPH, Michael T Yen, MD, Hashem Abu Serhan

Assigned editor:

Michael T Yen, MD

Review:

Assigned status Up to Date

 by Michael T Yen, MD on December 29, 2024.

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Contributing Editors:	add

The significance of numbers in routine clinical practice has grown exponentially. They guide disease diagnoses, treatment choices (in terms of kind, dosage, and duration), aid in surgical precision, determine implant specifications, and even influence follow-up schedules. Daily clinic procedures involve various biometric assessments, generating essential numerical data. In the realm of ophthalmology, sometimes, the sole focus for specialists is a single numeric value, such as normal corneal power, acceptable residual stromal bed levels, or specific anatomical reference values. Despite the advancement of search engines, procuring normal value ranges and their clinical implications remains a cumbersome task. Therefore, there's a strong appreciation among clinicians for a centralized repository of reference values in ophthalmology. This initiative aims to collect and present the latest reference values and their clinical relevance across various ophthalmic conditions. The primary source for these numbers is The American Academy of Ophthalmology's Basic and Clinical Science Course™ book series. Continuous contributions from all members are vital to maintain the page's accuracy and relevance.

Eye in Numbers

Adult Eye Volume

Parameter	Measurement
Adult eye volume	~6.5–7.0 mL

Axial Length (AL)

Condition	Measurement
Normal adult	23–25 mm
High myopia (> −6 D)	>26 mm
Pathologic myopia (> −8 D)	32.5 mm
Microphthalmia	<21 mm (adults), <19 mm (1 year of age)
Nanophthalmos	<18 mm (highly hyperopic eye)

   Clinical Pearls for Axial Length:
   * The standard Morcher CTR comes in three sizes based on uncompressed diameter, selected according to axial length (AL):
   ** 12.3 mm (compresses to 10 mm, Morcher 14): AL < 24 mm
   ** 13 mm (compresses to 11 mm, Morcher 14C): 24 mm < AL < 28 mm
   ** 14.5 mm (compresses to 12 mm, Morcher 14A): AL > 28 mm
   * Implant size calculation: Axial length − 2 mm = implant diameter
   ** Subtract 1 mm from implant diameter for evisceration and for hyperopia

Transverse Diameter of the Globe

Parameter	Measurement
Transverse diameter (widest point)	~24 mm

Cornea

Corneal Diameter

Category	Measurement
Adults (horizontal)	12–12.5 mm
Adults (vertical)	11 mm
At birth	9.5–10.5 mm

   Clinical Pearls for Corneal Diameter:
   * To calculate ACIOL size: Horizontal white-to-white distance + 1 mm
   * Congenital glaucoma:
   ** >12 mm horizontally in newborns
   ** >11.5 mm at birth
   ** >12.5 mm in 1-year-old children
   ** >13 mm in other children
   * Buphthalmos (“bull’s-eye”): Horizontal corneal diameter >13 mm
   * Megalocornea: >13 mm
   * Microcornea: <10 mm

Note: Adult size is reached by age 2 years.

Consistency

Parameter	Composition
Corneal dry weight	70% type I collagen

Corneal Power

Component	Power (D)
Average (air-tear interface)	43 D
Anterior	48–49 D
Posterior	−5.8 to −6 D

   Note: Posterior corneal surface contributes approximately 0.4 D of against-the-rule astigmatism.

   Clinical Pearls for Corneal Power:
   * Corneal plana: K < 43 D
   * Keratoconus:
   ** Central K > 47.2 D
   ** Inferior-superior (I-S) difference: >1.4 D in 3 mm
   ** Asymmetric K > 0.92 D
   * Risk for buttonhole with LASIK: K > 48 D
   * Risk for free flap with LASIK: K < 40 D
   * Predicting final K after LASIK:
   ** Myopia: Flattening of 0.80 D per D treated; avoid final K < 35–36 D
   ** Hyperopia: Steepening of 1.00 D per D treated; avoid final K > 50 D
   * Intacs in advanced keratoconus: K > 60.00 D has lower likelihood of functional vision improvement; corneal transplant may be needed

Asphericity:	Q value
Normal cornea is prolate	−0.26

Corneal Thickness

Structure/Location	Thickness
Central corneal thickness (CCT)	540 μm
Near limbus	700 μm – 1.0 mm
Limbal relaxing incision (LRI) depth	500–550 μm
Epithelium	50 μm (10% of corneal thickness)
Bowman layer	10 μm (8–14 μm)
Descemet membrane (at birth)	3 μm
Descemet membrane (adults)	10–12 μm

   Clinical Pearls for Corneal Thickness:
   * Risk for decompensation after intraocular surgery: CCT > 640 μm
   * Limbal/corneal relaxing incisions (LRI/CRI) depth: 500–600 μm (90% depth)
   * Arcuate or straight incisions (AK) depth: 99% depth (avoid >90° arc due to decreased efficacy and increased instability)
   * Radial keratotomy depth: 85–90% corneal thickness
   * Phototherapeutic keratectomy (PTK) depth: Ablate pathology in anterior 1/3 (~180 μm)
   * Contraindication for LASIK residual stromal bed (RSB): RSB < 250 μm or < 50% of original CCT
   * Contraindication for LASIK: CCT < 480 μm
   * Intacs: Lamellar channel at ~70% stromal depth (CCT − 50–60 μm)
   * Contraindication for ring/ICR: Thickness < 450 μm
   * Raindrop Near Vision Inlay: Placed at depth ≥ 200 μm
   * Contraindication for crosslinking (CXL): Thickness < 400 μm (some protocols allow > 300 μm)
   * LASIK flap thickness:
   ** Ultrathin: 80–100 μm
   ** Thin: 120 μm
   ** Standard: 120–180 μm
   * Using same microkeratome blade for fellow eye: Flap 10–20 μm thinner
   * Automated therapeutic lamellar keratoplasty: Microkeratome set for 130–450 μm

Endothelial Layer Characteristics

Endothelial Cell Density (ECD)

Age/Group	ECD (cells/mm²)
At birth	4000
Young adults	3000
Healthy 60 years old	2500–1500

Endothelial Cell Morphology

Parameter	Normal Range
Mean cell size/area	150–350 μm²
Coefficient of variation (CV) index	<0.40
Hexagonality (6A)	>50%

   Clinical Pearls for Endothelial Layer:
   * Not appropriate for donation: ECD < 2000 cells/mm²
   * Risk for decompensation after intraocular surgery: ECD < 1000 cells/mm²
   * Contraindication for intraocular surgery: ECD < 500 cells/mm²
   * Risk for corneal decompensation after intraocular surgery:
   ** Polymegathism: CVI > 0.4
   ** Pleomorphism: Hexagonality < 50%
   * Note: ECD decreases approximately linearly until age 60, then at a lower rate, so older adults (70–80 years) may have more cells than expected.

Conjunctiva

Feature	Measurement/Note
Limbus integrity	At least 25%–33% must remain intact for normal resurfacing
Giant papillae size	>1 mm
Margin of excision with SCC	Wide excision (4 mm margin)

   Clinical Pearls 
   Note: Limbus integrity is critical in chemical burns or ocular surface tumor surgeries.

Sclera

Location	Thickness (mm)
Posterior to recti insertions (thinnest)	0.3
At the equator	0.4–0.5
Anterior to muscle insertions	0.6
Around optic nerve head (thickest)	1.0

   Clinical Pearls for Sclera:
   * The thinnest part (0.3 mm, posterior to recti insertions) is significant in blunt trauma and scleral laceration.
   * For drainage of suprachoroidal hemorrhage, sclerotomy is placed 5–6 mm posterior to the limbus, primarily in the inferotemporal quadrant.

Anterior chamber

Parameter	Measurement
Anterior chamber depth (ACD)	3 mm
Critical angle for total internal reflection (air-tear interface)	46 degrees

   Clinical Pearls 
   * If ACD <2.0 mm: Risk factors for angle closure
   * If ACD <3.2 mm: Increased risk of endothelial/iris trauma with phakic IOL placement

Aqueous humor

Parameter	Measurement
Total volume	260 μL
Daytime production rate	2-3 μL/min (renews every 100 min)
Nighttime production rate	1 μL/min (renews every 200 min)
Ascorbic acid concentration	10-50× plasma levels

Chambers

Chamber	Volume
Anterior chamber (AC)	200 μL
Posterior chamber (PC)	60 μL

   Clinical pearls:
   AC tap/paracentesis Withdraw 0.05-0.1 cc using 27-30G needle near limbus

Phakic IOL

Parameter	Measurement
Vault	250-750 μm (0.5-1.5× CCT)

   Clinical pearls:
   * Vault <90 μm increases anterior subcapsular cataract risk

Intraocular pressure (IOP)

Population	Normal range (mmHg)
Adults	10-21
7-year-olds	14
Newborns	10-12

   * Pediatric glaucoma: IOP >10-15 mmHg considered abnormal
   * Congenital glaucoma infants: Typically 30-40 mmHg (20 mmHg under anesthesia)

Episcleral venous pressure

Measurement	Value
Normal EVP	6-9 mmHg

Pupil

Parameter	Measurement
Light reflex development	≥30 weeks GA
Diameter (light)	2-4 mm
Diameter (dark)	4-8 mm
Airy-disk size	1.2 mm
Anisocoria threshold	>1 mm difference

Iris

Parameter	Measurement
Thickness	0.35-0.45 mm

   Clinical pearls:
   * Abnormal thickness: >0.7 mm
   * Iridotomy size: ≥150-200 μm (ideal 500 μm)

Lens

Parameter	Measurement
Refractive index	1.4
Dioptric power	20 D
Diameter (neonate)	6.5 mm
Diameter (adult)	8.54-9.70 mm

Capsule

Location	Thickness
Anterior	14.0-15.5 μm
Posterior (thinnest)	2.8-4.0 μm
Post. pre-equatorial (thickest)	23 μm

   Clinical pearls:
   * Optimal capsulorhexis: 5.5-6 mm
   * Piggyback IOL: 1.2× RE (myopia), 1.5× RE (hyperopia)

Ciliary body

Feature	Count
Ciliary processes	70

Pars plana

Population	Injection site
Phakic adults	3.5-4 mm posterior
Pseudophakic/aphakic	3-3.5 mm posterior
1-6 months	1.5 mm
6-12 months	2 mm
1-2 years	2.5 mm
2-6 years	3 mm

Ora serrata

Location	Distance from limbus
Nasal	5.75 mm
Temporal	6.50 mm

   Clinical pearls:
   * Prefer temporal quadrant for intravitreal injections

Vascularization

Event	Timing
Nasal retina maturation	36 weeks GA
Temporal retina maturation	40 weeks GA*
Full vascularization	3 months postnatal
Choroid development	16 weeks GA

   Clinical pearls:
   * Begin ROP screening from observing temporal area.

Vitreous

Structure	Volume
Vitreous cavity	5-6 mL
Vitreous body	4 mL

   Clinical pearls: Vitreous sampling
   * Pars plana vitrectomy: 0.2-0.5 mL
   * Vitreous tap: 0.1-0.3 mL

Consistence	%
water	90

Macula

Parameter	Measurement
Diameter	5.5 mm

Macula, perifovea, parafovea, fovea, foveola.

   * Distance between optic disc-macula >3 DD suggests optic nerve hypoplasia

Fovea

Feature	Measurement
Diameter	1.5 mm (5°)
Photostress recovery time	>90 seconds indicates maculopathy

   Clinical pearls:
   * Monovision syndrome: 8 prism diopter deviation
   * Rhodopsin sensitivity: 510 nm (green light)

Foveal avascular zone (FAZ)

Parameter	Measurement
Diameter	500 μm (1:40°)

   Clinical pearls: Avoid laser therapies in FAZ

Foveola

Parameter	Measurement
Location (temporal to disc)	4.0-4.5 mm (15°)
Location (inferior to disc)	0.8 mm (2:10°)
Diameter	350 μm

Umbo

Parameter	Measurement
Diameter	150 μm

ParaFovea

Parameter	Measurement
Ring width	0.5 mm
Outer radius	2.5 mm
Inner radius	1.5 mm

PeriFovea

Parameter	Measurement
Ring width	1.5 mm
Outer radius	5.5 mm
Inner radius	2.5 mm

Optic nerve

Parameter	Measurement
Adult axons	1.2-1.5 million
Gestational axons (16 weeks)	3.7 million
Head diameter	1.5-2.2 mm
Cup-to-disc ratio (normal)	<0.5
Total length	50 mm

   Clinical pearls:
   * NAION risk: Cup-to-disc ratio ≤0.2 ("disc-at-risk")
   * Enucleation in retinoblastoma: Excise ≥10 mm ON
   * Atrophy timeline: 6 weeks post-damage

Retinal pigment epithelium (RPE)

   Clinical pearls:
   * PED >600 μm height risks RPE tear post anti-VEGF
   * EOG Arden ratio:
     - Normal: >2
     - Best disease: ≤1.5

Choroid

Feature	Risk Threshold
Nevus thickness	>2 mm (melanoma risk)

Vascular anatomy

Structure	Count
Short posterior ciliary arteries	20
Short posterior ciliary nerves	10
Long ciliary arteries/nerves	2

Extraocular muscles

Muscle	Active Length	Tendon Length*
Rectus muscles	40 mm	4.5-7 mm
Superior oblique	32 mm	26 mm
Inferior oblique	37 mm	1 mm
Levator	40 mm	14-20 mm

(*)Shortest tendon (I M SIL Live So):

• IO:1 mm
• MR:4.5 mm (shortest between rectus muscles)
• Overal length:
  • Longest: SO (58 mm) >Levator>others>Shortest: IO (38 mm)

Insertion distances

Muscle	Distance from Limbus
MR	5.5 mm
IR	6.5 mm
LR	6.9 mm
SR	7.7 mm

Arc of contact

Muscle	Contact Length
IO*	15 mm
LR	12 mm
SO	7-8 mm
MR**	7 mm

(*)IO:(Longest) (**)MR:(Shortest)

• • • LR inserts 2 mm more superior than MR.
  • EOM penetrate the tenon capsule 10 mm posterior to their insertions.

Orbit

Parameter	Measurement
Volume	<30 cm³
Posterior globe-optic foramen	18 mm
Interpupillary distance	60-62 mm
Intercanthal distance	30-31 mm

   Clinical pearls:
   * Exophthalmos: ≥2 mm asymmetry
   * Hypertelorism: IPD >2 SD above mean
   * Telecanthus: Intercanthal >2 SD

Ciliary ganglion

Location	Measurement
Anterior to annulus of Zinn	1 cm

Tear and Tear-Film

Parameter	Measurement
Tear lake volume	7-10 µL
Eyedrop retention rate	20% (10 µL of 50 µL)
Tear production onset	20 days postnatal
Lacrimal gland maturation	6 weeks postnatal

   Clinical pearls:
   * One eyedrop bottle = 5 mL ≈ 100 drops (50 µL/drop)
   * Atropine 1% example: 0.5 mg/drop → 50 mg/bottle
   * Artificial tears ideal properties:
     - pH 7.0-8.2
     - Osmolarity ≤302 mOsm/L

Tear Composition

Layer	Component	Percentage
Aqueous	Water	98%
	Total protein	2%
	Lysozyme	30% of protein
	Lactoferrin	-
	Immunoglobulins	IgA, IgG
	pH	7.2
Osmolarity	302 mOsm/L
Basal secretion	2 µL/min

Layer	Production Rate
Mucin (inner)	2-3 mL/day

Dry Eye Diagnostics

Test	Normal	Abnormal
Dye disappearance test (DDT)	≤5 min	>5 min (NLDO)
Tear breakup time	≥10 sec	<10 sec
Tear meniscus height	≥0.3 mm	<0.2 mm
Phenol red thread	≥10 mm/15s	<10 mm/15s
MMP-9 level	≤40 ng/mL	>40 ng/mL

Schirmer Tests

Test	Method	Interpretation
Basic Secretion	Anesthetized	<3 mm/5 min = ATD
Schirmer I	Non-anesthetized	<5.5 mm/5 min = ATD
Schirmer II	Nasal stimulation	<15 mm/2 min = Reflex defect

   Key:
   ATD = Aqueous Tear Deficiency
   NLDO = Nasolacrimal Duct Obstruction
   MMP-9 = Matrix Metalloproteinase-9

Developmental Timeline

Milestone	Timing	Clinical Significance
First tears	20 days	NLDO signs appear
Lacrimal function	6 weeks	Full secretory capacity

Eyelid Anatomy

Structure	Measurement
Upper tarsal height	11 mm (3× lower tarsus)
Lower tarsal height	4 mm
Palpebral fissure height	10-11 mm (women: 9-11 mm, men: 7-8 mm)
MRD1	3-4 mm
MRD2	5 mm
Eyelid length	30 mm

   Clinical pearls:
   * MRD1 ↑ with lid retraction, ↓ with ptosis

Arterial Supply

Vascular Structure	Location
Marginal arcade*	2-3 mm superior to lash line
Superior peripheral arcade	Within/between Müller's muscle & levator aponeurosis

   Clinical pearls:
   (*) Marginal arcade avoid them while performing tarsoraphy.

Upper Lid Crease

Measurement	Distance
Brow to crease	10 mm
Crease to margin (women)	8-10 mm
Crease to margin (men)	6-8 mm

   Clinical pearls:
   ** Congenital ptosis: Absent lid crease
   **Involutional ptosis: Elevated crease position

Blinking Frequency and Clinical Significance

Blinking Frequency	Normal Range	Clinical Significance
Normal	12-20 blinks per minute	Maintains tear film stability, prevents dryness, and clears debris from the ocular surface.
Reduced (Hypoblinking)	<10 blinks per minute	Seen in Parkinson’s disease, ocular surface disease, or neurogenic causes; increases risk of dry eye syndrome and exposure keratopathy.
Increased (Hyperblinking)	>20-25 blinks per minute	Associated with blepharospasm, ocular irritation, tic disorders, or psychological stress.
Asymmetrical Blinking	Varies between eyes	Suggests facial nerve palsy (e.g., Bell’s palsy) or neuromuscular dysfunction affecting one eyelid.

    Clinical Pearls:
    * Normal blinking occurs every **3-5 seconds**, with complete closure ensuring corneal hydration.
    * Incomplete blinking: can lead to exposure keratopathy and is commonly seen in lagophthalmos or after aggressive ptosis surgery.
    * Patients with neurogenic hypoblinking (e.g., Parkinson’s) may require lubricating drops or eyelid training exercises to prevent corneal damage.

Levator Function

Classification	Excursion
Normal	>12 mm
Fair	6-11 mm
Poor	<6 mm

Levator Function and Surgical Guidelines

Levator Function	Recommended Surgery	Indications
Excellent (>12 mm)	Mild ptosis: Müller’s muscle resection or small levator advancement	Small droop, strong muscle, good phenylephrine test response
Good (8-12 mm)	Levator advancement/resection for moderate ptosis	Aponeurotic or mild congenital ptosis with functional levator
Fair (5-7 mm)	Moderate-to-severe ptosis: Levator resection (maximal if needed)	Levator has some function, can attempt resection but results may vary
Poor (<4 mm)	Frontalis sling (bypassing weak levator function)	Severe congenital ptosis, third-nerve palsy, muscular dystrophy-related ptosis

   Clinical pearls:
   * Levator resection indicated when LF >4 mm
   * Normal excursion: ~15 mm (range 12-18 mm)

Meibomian Glands

Location	Gland Count	Secretory Rate
Upper eyelid	25-40	1.0-1.4 μL/min
Lower eyelid	20-30	0.8-1.2 μL/min

Eyelashes

Parameter	Measurement
Upper lid count	90-150
Lower lid count	70-80
Growth rate	0.12-0.15 mm/day
Full regrowth time	6 weeks (intact follicle)

   Clinical pearls:
   * Post-epilation recovery: 6-12 weeks for full growth
   * Repeated extension use may reduce lash density by 30-50%
   * Bimatoprost increases length by 25-30% but may cause periocular pigmentation

Growth Cycle

Phase	Duration	Characteristics
Anagen	30-45 days	Active growth
Catagen	2-3 weeks	Follicle regression
Telogen	30-45 days	Resting/shedding

Biopsy Guidelines

   Clinical pearls: Biopsy size and width of margins should be based on clinical presentation, level of suspicion, and risk factor analysis.

Ophthalmic Instruments

Device	Specification
Goldmann tonometer	3.06 mm applanated area 1.25g weight (5.5g total force)
LASIK plume particles	0.22 µm size
Surgical mask filtration	0.1 µm efficiency

   Clinical pearls:
   * LASIK safety: 
   ** A canister mask  will filter these particles down to 0.1 µm.
   ** The average particles produced in the LASIK plum  are 0.22 µm.
   ** N95 masks  filter 95% of 0.3µm particles

Volk Lens Factors

Lens	Magnification Factor	Field Width
60D	1.0×	70°
78D	1.1×	85°
90D	1.3×	100°

   Clinical pearls:
   * 60D lens: 1:1 papilla-to-slit beam ratio at 16× magnification

Visual Acuity Testing

Test	Parameter	Specification
Pinhole	Optimal diameter	1.2 mm (corrects ≤3D)
Pinhole	Diffraction limit	20/40 at 1.0 mm

Nystagmus Acuity Estimates

Type	Visual Acuity	Characteristics
Vertical OKN	≥20/400	Vertical nystagmus overlay
Searching	<20/200	Roving eye movements
Pendular	>20/200	Sinusoidal oscillation
Jerk	20/60-20/100	Fast/slow phases

Preschool HOVT Norms

Age	Snellen	Decimal
2.5y	20/63-20/30	0.33-0.66
5y	20/30-20/20	0.66-1.0

Duochrome Testing

Source	Chromatic Interval	Wavelength Difference
Commercial filters	0.50D	490nm vs 630nm
Human eye (Fraunhofer)	1.5-3.0D	486nm (F) - 656nm (C)
Human eye (Helmholtz)	1.8D	Photopic sensitivity peak

   Clinical pearls:
   * 80% patients prefer green focus at 0.25D over red[9][10]
   * 1.0D hyperopia correction improves duochrome balance by 40%[11]

Time-Critical Ophthalmic Protocols

Emergency Interventions

Condition	Time Window	Specifics
Myocardial Infarction/Stroke/CRAO	≤90 min	Door-to-balloon/thrombolysis
Sympathetic Ophthalmia	4-8 weeks (65% 2-8w, 90% <1y)	Latent period post-trauma
Hyphema (Pediatric)	4-5 days	Surgical intervention threshold
Hyphema (Sickle Cell)	>24h IOP >25 mmHg	Immediate surgery
Perforating Trauma	5-14 days	Vitrectomy for PVR prevention

Surgical Timing

Procedure	Minimum Wait	Details
LASIK Re-treatment	3 months	Refractive stability required
Surface Ablation Repeat	6-12 months	Haze resolution period
Nerve Palsy Repair	9-12 months	Allow spontaneous recovery
**Refractive Surgery Post-Pregnancy**	**3 months postpartum + breastfeeding cessation**	Hormonal stabilization
Congenital Cataract (Uni)	<6 weeks	Prevent sensory nystagmus
Congenital Cataract (Bi)	<8-10 weeks	Sequential within 2w (<2y) /4w (>2y)
Artificial Iris Implant	≥16 years	Pediatric contraindication

Pharmacological Timelines

Medication	Critical Duration	Effects
**Topical Steroids**	>2w use → 5% IOP >31mmHg at 6w ≥18mo → Permanent damage	Monitor IOP q2w, If > 3 drops/d>3mo consider systemic
Systemic Steroids (Immunosuppression)	>7.5mg/d >3mo	Threshold for alternative therapy
Tetracaine	10-20s onset	10-20min duration
**Retrobulbar Lidocaine (0.5-2%)**	5min onset	1-2hr akinesia
Δ9-THC (Marijuana)	3-4hr	Impractical IOP control

Cycloplegics/Mydriatics (ASH-CT Mnemonic)

Agent	Duration	Full Effect Onset
**A**tropine	7-14d	60-120min
**S**copolamine	4-7d	45min
**H**omatropine	3d	30min
**C**yclopentolate	24hr	60min
**T**ropicamide	4-6hr	30min

Diagnostic Protocols

Test	Protocol	Positive Criteria
**Tensilon (Edrophonium)**	2+4+4mg IV + **Atropine pre-treatment**	≥2mm lid elevation
**Neostigmine**	1.5mg IM + Atropine 0.6mg IV	Improvement in 30-45min
Sleep Test	30min nap	Lid elevation + resolution
Ice Pack Test	2min application	≥2mm improvement

Specialized Procedures

Technique	Exposure Time	Clinical Application
Absolute Alcohol (20%)	10–45s	Epithelial debridement
Mitomycin C (0.02%)	12s–2min	Haze prevention
**Photodynamic Therapy**	N/A	**5d strict sun avoidance**

   Clinical Pearls:
   1. **Steroid Response Gradation:**
      - <2w: Rare IOP spikes
      - 6w: 5% >31mmHg
      - ≥18mo: 22% permanent damage
   2. **MG Crisis Protocol:**
      - Neostigmine 1.5mg IM + Atropine 0.6mg IV q4-6h
   3. **ONTT Steroid Taper:**
      - Prednisone 1mg/kg/day ×11d → 20mg day 12 → 10mg days 13-15
   4. **GCA Biopsy:**
      - 2-3cm specimen length (skip lesion prevention)

Disease Timelines & Definitions

Condition	Time Criteria	Clinical Significance
Apparent Optic Atrophy	6 weeks post-injury	Final functional assessment window

Uveitis Classification

Type	Duration	Recurrence Pattern
Acute	<3 months	Single episode
Recurrent	<3 months/episode	>3 months between flares
Chronic	>3 months	Persistent inflammation

Diabetic Retinopathy Screening

Population	Initial Exam	Pregnancy Protocol
Type 1 DM	3-5 years post-diagnosis	1st trimester
Type 2 DM	At diagnosis	1st trimester

   Clinical pearls:
   * 15% of Type 1 DM develop DR within 5 years
   * 20% of Type 2 DM have DR at diagnosis
   * Monthly exams for proliferative DR in pregnancy

Intraocular Gas Dynamics

Gas	Effective Tamponade	Retention Time	Key Properties
SF₆	6 days	13 days (2-3w)	Non-expansile concentration
C₂F₆	15 days	35 days (3-4w)	18% concentration expands 2×
C₃F₈	30 days	65 days (6-8w)	14% concentration expands 4×

   Clinical pearls:
   * SF₆: Requires 5-day face-down positioning
   * C₃F₈: 20% risk of transient IOP >30mmHg (monitor q4h first day)
   * Gas-filled eyes contraindicated for air travel until 10% residual

Gas Selection Guide

Clinical Scenario	Preferred Gas	Rationale
Macula-on RD	SF₆	Short-term tamponade needed
Giant retinal tear	C₂F₆	Moderate duration support
Proliferative vitreoretinopathy	C₃F₈	Long-term stabilization

   Key:
   RD = Retinal Detachment
   IOP = Intraocular Pressure
   w = weeks
   DM = Diabetes Mellitus
   DR = Diabetic Retinopathy

• When different antiplatelets or anticoagulants should be paused before various intraocular or oculoplastic surgeries:

Timing of Pausing Antiplatelets and Anticoagulants Before Intraocular or Oculoplastic Surgery

Medication	Intraocular Surgery (e.g., Cataract, Glaucoma, Vitrectomy)	Oculoplastic Surgery (e.g., Blepharoplasty, Ptosis repair)	Comments
Aspirin	*	7-10 days before	*May continue in minor surgeries if risk of thromboembolism is high.
Clopidogrel (Plavix)	5-7 days before	5-7 days before	Consider bridging with low-dose aspirin if thromboembolic risk is high.
Ticagrelor (Brilinta)	5-7 days before	5-7 days before	Bridging therapy might be considered depending on the thromboembolic risk.
Prasugrel (Effient)	7-10 days before	7-10 days before	Typically requires longer cessation than clopidogrel due to higher potency.
Warfarin (Coumadin)	3-5 days before	3-5 days before	INR should be normalized (<1.5); consider bridging with LMWH if high risk.
Dabigatran (Pradaxa)	2-3 days before	2-3 days before	Consider longer cessation (4-5 days) in patients with renal impairment.
Rivaroxaban (Xarelto)	2-3 days before	2-3 days before	Discontinue 2 days before surgery for normal renal function; may require more if renal function is impaired.
Apixaban (Eliquis)	2-3 days before	2-3 days before	May consider 48-hour cessation, longer if impaired renal function.
Edoxaban (Savaysa)	2-3 days before	2-3 days before	Similar considerations as for other direct oral anticoagulants.
Heparin (Unfractionated)	4-6 hours before	4-6 hours before	Short-acting; can be paused closer to the surgery.
Low Molecular Weight Heparin (LMWH)	24 hours before	24 hours before	Enoxaparin typically paused 24 hours prior; consider renal function.
NSAIDs (e.g., Ibuprofen)	48-72 hours before	48-72 hours before	Avoid in cases where bleeding risk is significant.

• Discontinuing aspirin before cataract surgery is a practice driven by theoretical risks of bleeding, despite strong evidence from large-scale studies and meta-analyses showing that continuing aspirin does not significantly increase serious complications but poses real thrombotic risks and unnecessary healthcare disruptions.

Critical Ophthalmic Dosages

Antimalarials

Parameter	Hydroxychloroquine	Chloroquine
Daily Dose	5.0 mg/kg (actual body weight)	2.3 mg/kg (actual body weight)
Cumulative Toxicity Threshold	>1000 g total	>460 g total
High-Risk Duration	>5 years	>5 years

   Clinical pearls:
   * Use actual body weight for all BMI categories
   * Annual retinal screening mandatory after 5 years of use
   * Discontinue if retinal toxicity suspected

Toxoplasmosis Management

Prophylaxis

Scenario	Regimen	Duration
Paramacular recurrence	TMP-SMX 800/160mg q3d	Long-term
Perioperative (LASIK/Phaco)	TMP-SMX 800/160mg daily	2 days pre-op → 1 week post-op

Adult Treatment

Medication	Loading Dose	Maintenance	Adjuncts
Pyrimethamine	200mg Day 1	50mg daily ×4wk	Folinic acid 15mg BIW
Sulfadiazine	2g Day 1	1g QID ×4wk	Hydration + NaHCO₃

Alternate Regimens

Option	Dose	Frequency
Azithromycin	500mg	Daily ×4wk
Clindamycin	300-450mg	q6h ×4wk
TMP-SMX DS	1 tablet	BID ×4wk

Vision-Threatening Lesions

Medication	Dose	Administration
Prednisone	1-1.5 mg/kg/day	4-week taper
Triamcinolone	40mg	Single periocular injection

   Clinical pearls:
   * Start steroids 72h after antimicrobial initiation
   * Prepare TMP-SMX DS as double-strength tablets (160/800mg)

Congenital Toxoplasmosis

Medication	Dose	Frequency
Pyrimethamine	1mg/kg	q3d ×3wk
Sulfadiazine	50-100mg/kg	BID ×3wk
Folinic Acid	3mg	BIW during treatment

   Clinical pearls:
   * Pregnancy management: Spiramycin 1g TID for acute maternal infection
   * Corticosteroid taper duration: 2-4 weeks based on response

Herpesviridae Therapy

HSV Treatment

Medication	Acute Therapy	Prophylaxis
Acyclovir	400mg 5×/day	400mg BID
Valacyclovir	1000mg TID	500-1000mg daily
Famciclovir	250mg TID	250mg BID

HZO Treatment

Medication	Dose	Duration
Acyclovir	800mg 5×/day	10-14 days
Valacyclovir	1g TID	10-14 days
Famciclovir	500mg TID	10-14 days

   Clinical pearls:
   * Recurrent HZO: Extend antiviral course to 21 days
   * Topical steroids: Prednisolone 1% q2-6h based on severity
   * Chronic prophylaxis: Reduce dose by 50% after 6 months

Intracameral Medications

Medication	Concentration	Volume	Preparation Notes
Cefuroxime	1 mg	0.1 mL	Standard reconstitution
Moxifloxacin	150 µg/0.1 mL	0.3-0.4 mL	3 mL Vigamox + 7 mL BSS

   Clinical pearls:
   * Inject moxifloxacin as final surgical step
   * Maintain strict aseptic technique during dilution

Intravitreal Injections

Medication	Dose	Indication	Notes
Bevacizumab	1.25 mg/0.05 mL	Off-label use	0.675 mg/0.03 mL for ROP
Ranibizumab	0.5 mg/0.05 mL 0.3 mg/0.05 mL	nAMD/RVO DR/DME	Myopic CNVM
Aflibercept	2.0 mg/0.05 mL	VEGF-mediated diseases	-
Brolucizumab	6 mg/0.05 mL	nAMD	-
Faricimab	6 mg/0.05 mL	DME/nAMD	-
Triamcinolone	2 mg/0.05 mL 4 mg/0.1 mL	Off-label	Use Triesence®/Trivaris® for FDA-approved
Ganciclovir	4 mg/0.1 mL	CMV retinitis	2 mg/0.05 mL twice weekly ×14d
Clindamycin	1 mg/0.1 mL	Toxoplasmosis	-
Foscarnet	2.4 mg/0.1 mL	Viral retinitis	1.2 mg/0.05 mL dose
Fomivirsen	330 mcg/0.05 mL	CMV retinitis	-
Methotrexate	400 mcg/0.1 mL	Intraocular lymphoma	-
Vancomycin	1 mg/0.1 mL	Endophthalmitis	-
Ceftazidime	2.25 mg/0.1 mL	Bacterial infections	-
Amikacin	0.4 mg/0.1 mL	Gram-negative coverage	-
Amphotericin B	5 mcg/0.1 mL	Fungal infections	-
Voriconazole	50-100 mcg/0.1 mL	Fungal endophthalmitis	-
Dexamethasone	0.4 mg/0.1 mL	Inflammation	-

   Clinical pearls:
   * Use 30G needles for all intravitreal injections
   * Confirm needle position in mid-vitreous
   * Monitor IOP post-injection

Fortified Ocular Topicals

Medication	Concentration	Preparation Method
Bacitracin	10,000 IU/mL	Reconstitute powder with sterile water
Cefazolin	50 mg/mL (5%)	500mg vial + 10mL sterile saline
Ceftriaxone	50 mg/mL (5%)	1g vial diluted in 20mL artificial tears
Ceftazidime	50 mg/mL (5%)	1g vial + 10mL BSS + 10mL vehicle
Vancomycin	50 mg/mL (5%)	500mg vial + 10mL sterile water
Linezolid	2 mg/mL (0.2%)	IV solution diluted 1:10 with saline
Gentamicin	14 mg/mL (1.4%)	80mg injectable + 5mL commercial drops
Tobramycin	14 mg/mL (1.4%)	Same as gentamicin
Amikacin	40 mg/mL (4%)	500mg vial + 12.5mL vehicle
Clarithromycin	10 mg/mL (1%)	500mg tablet dissolved in 50mL vehicle
Azithromycin	10 mg/mL (1%)	Reconstitute powder with sterile water
Co-trimoxazole	16/80 mg/mL (TMP/SMX)	80/400mg tablet in 50mL vehicle

   Clinical pearls:
   * Refrigerate at 4°C; discard after 7 days (14 days for vancomycin)
   * Use preservative-free artificial tears as base vehicle
   * Shake suspensions vigorously before administration
   * Monitor corneal epithelium daily with aminoglycosides
   * TMP/SMX ratio maintained at 1:5 (16mg:80mg)

References:

1. 2022-2023 Basic and Clinical Science Course, Section 01: Update on General Medicine by Herbert J. Ingraham , ISBN: 9781681045412 , Publication Date: 2022-08-30

2. 2022-2023 Basic and Clinical Science Course, Section 02: Fundamentals and Principles of Ophthalmology by Vikram S. Brar Section 2 , ISBN: 9781681045429, Publication Date: 2022-08-30

3. 022-2023 Basic and Clinical Science Course, Section 03: Clinical Optics and Vision Rehabilitation by Scott E. Brodie , ISBN: 9781681045436, Publication Date: 2022-06-20

4. 2022-2023 Basic and Clinical Science Course, Section 04: Ophthalmic Pathology and Intraocular Tumors by Nasreen A. Syed ISBN: 9781681045443, Publication Date: 2022-06-20

5. 2022-2023 Basic and Clinical Science Course, Section 05: Neuro-Ophthalmology by M. Tariq Bhatti, ISBN: 9781681045450, Publication Date: 2022-06-20

6. 2022-2023 Basic and Clinical Science Course, Section 06: Pediatric Ophthalmology and Strabismus by Arif O. Khan, ISBN: 9781681045467, Publication Date: 2022-06-20

7. 2022-2023 Basic and Clinical Science Course, Section 07: Oculofacial Plastic and Orbital Surgery by Bobby S. Korn, ISBN: 9781681045474, Publication Date: 2022-06-20

8. 2022-2023 Basic and Clinical Science Course, Section 08: External Disease and Cornea by Robert W. Weisenthal, ISBN: 978168104548, Publication Date: 2022-06-20

9. 2022-2023 Basic and Clinical Science Course, Section 09: Uveitis and Ocular Inflammation by H. Nida Sen, ISBN: 9781681045498, Publication Date: 2022-06-20

10. 2022-2023 Basic and Clinical Science Course, Section 10: Glaucoma by Angelo P. Tanna, ISBN: 9781681045504, Publication Date: 2022-06-20

11. 2022-2023 Basic and Clinical Science Course, Section 11: Lens and Cataract by Linda M. Tsai, ISBN: 9781681045511, Publication Date: 2022-06-20

12. 2022-2023 Basic and Clinical Science Course, Section 12: Retina and Vitreous by Stephen J. Kim, ISBN: 9781681045528, Publication Date: 2022-06-20

13. 2022-2023 Basic and Clinical Science Course, Section 13: Refractive Surgery by M. Bowes Hamill Restricted Resource, ISBN: 9781681045535, Publication Date: 2022-06-20

14. Nixon HK. Preparation of fortified antimicrobial eye drops. Kerala J Ophthalmol [serial online] 2018 [cited 2022 Dec 23];30:152-4. Available from: http://www.kjophthal.com/text.asp?2018/30/2/152/239986

15. https://eyewiki.aao.org/Herpes_Simplex_Uveitis#Medical_therapy

16. https://www.aao.org/current-insight/management-of-ocular-toxoplasmosis