Cornea

Baby picture of the day!

Sodium Fluorescein

Used to stain dead or devitalized cells on the cornea and conjunctiva

Pooling: green pools of fluorescein caused by dips in the tissue

Negative staining: areas with no staining caused by elevation in the tissue

Keratopathies

Dellen Exposure

keratopathy Filamentary

keratopathy Superficial punctate

keratitis

Thygeson’s superficial punctate keratopathy

Neurotrophic keratopathy

Recurrent corneal erosion

Thermal/UV keratopathy

Dellen

Stromal dehydration Fluorescein pooling

Superficial Punctate Keratitis (SPK)

Non-specific inflammation of epithelium

Causes: contact lenses, infection, dry eye, blepharitis, allergy/toxicity, trichiasis, etc.

Exposure Keratopathy

Eyelid problem – incomplete closure

#1 cause: nocturnal lagophthalmos

Other causes: surgery, nerve palsy, CVA, thyroid eye disease, floppy eyelid syndrome

Filamentary Keratopathy

Filaments = epithelial cells + mucous

#1 cause: keratoconjunctivitis sicca

Dryness lids scrape against

cornea friction chronic inflammation

Thygeson’s Superficial Punctate Keratopathy

Young adult patients White conjunctiva with

“crumb-like” central cornea

Cluster of elevated white lesions in central cornea

Lesions don’t stain (unlike SPK)

Bilateral

Neurotrophic Keratopathy

Think CN V1 (nasociliary)

Trigeminal neuropathy from damage to the nerve

Decreased corneal sensitivity decreased wound healing

Bad combination!

Recurrent Corneal Erosion (RCE)

Poor hemidesmosome attachments between epithelium & BM due to previous trauma

Patient awakens with acute pain

Thermal/UV Keratopathy

UV-C (<300nm) is absorbed by the cornea

Causes: sun, welding, snow, tanning

Signs: SPK Symptoms: pain,

photophobia, blur Symptoms begin 6-12

hours later!

Dry Eye Syndrome (DES): Definition

A “multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface.”

Associated systemic diseases: thyroid, arthritis, Sjogren’s, SLE

Problematic meds: anticholinergic, antihistamines, hormone replacement, diuretics

DES: Testing

Schirmer 1: no anesthetic, normal >10mm/5min

Schirmer 2: anesthetic, normal >5mm/5min

Phenol red thread: pH sensitive, normal >10mm/15sec

Tear osmolarity Tear film instability (TBUT)

DES: Categories

Aqueous tear-deficient

Lack of lacrimal secretion Sjogren’s: includes

autoantibodies & dry mouth

Non-Sjogren’s = Lacrimal gland deficiency

Evaporative

Water loss with normal lacrimal secretion

Intrinsic = due to lid pathology

Extrinsic = no lid pathology (vitamin deficiency, preservatives)

Keratoconus Pellucid Marginal Degeneration (PMD) Keratoglobus

All 3 can cause hydrops (tears in Descemet’s membrane)

Ectasias

Keratoconus

Presents at puberty History of atopy Collagen fibril

displacement, corneal thinning, corneal protrusion

Fleischer’s ring = iron deposit at base of cone

Pellucid Marginal Degeneration (PMD)

Presents in young adults

Inferior thinning/protrusion of the cornea

Against the rule (ATR) astigmatism = “kissing doves” / “crab claws” on topography

Keratoglobus

From birth General corneal

thinning, worst in periphery

Easier to perforate cornea

Dystrophies

Anterior

EMBD Meesman’s Reis-Buckler

Stromal

Macular Granular Lattice Schnyder’s

Posterior

Fuch’sPosterior Polymorphous

All of these are autosomal dominant (AD) except macular dystrophy (AR)

EBMD = Map-Dot Fingerprint

Epithelial Basement Membrane Dystrophy (EBMD)

Excessive basement membrane production

Can cause recurrent corneal erosions

Negative staining shaped like map lines or fingerprints

Fuch’s Endothelial Dystrophy

Older female patients Excess production of

posterior lamina (Descemet’s membrane)

Signs: guttata (clumps of Descemet’s BM), decreased endothelial cell density, stromal edema

Symptoms: blurry vision am

Congenital Anomalies of the Cornea

Megalocornea Microcornea Cornea plana Aniridia

Haab’s Striae Axenfeld-Rieger

syndrome Peter’s Anomaly Limbal dermoid

Megalocornea & Microcornea

Megalocornea

X-linked Diameter >13mm Myopic pts

Microcornea

AD or AR inheritance Diameter <10mm Hyperopic pts

Cornea Plana

AD or AR inheritance Corneal curvature

equals scleral curvature

Flat cornea

Aniridia

Bilateral, AD inheritance

Lack of iris tissue Often accompanied

by foveal hypoplasia (reduces VA) & colobomas

Haab’s Striae

Horizontal lines in Descemet’s membrane

Occurs in congenital glaucoma

Peter’s Anomaly

Present at birth Bilateral White cornea

(leukoma)

Bacterial Keratitis Fungal Keratitis Acanthamoeba Keratitis Herpes Simplex Virus (HSV) Herpes Zoster Virus (HZV)

Infectious Keratitis

Bacterial Keratitis

Most common infectious keratitis

Staphylococcus, Pseudomonas, Haemophilus influenzae, Moraxella catarrhalis

Ulcer = infiltrates (immune) + epithelial defect

Infectious ulcers stain

Fungal Keratitis

Feathery edges Caused by plant

trauma Candida infection

indicates immune compromise

Acanthamoeba Keratitis

Contact lens abuse (tap water)

Pain out of proportion to signs

Ring ulcer

DNA virus that infects the trigeminal ganglion (CN5)

Decreases corneal sensitivity Type 1 (top) vs. Type 2 (bottom) Transmission

Herpes Simplex Virus (HSV)

HSV

Epithelial Disease

Dendritic ulcers (stain)

Geographic ulcers (stain)

Neurotrophic Keratitis

Reduced innervation to cornea

Poor wound healing & reduced sensation

HSV

Stromal Disease

Interstitial keratitis = neovascularization, immune ring, stromal thinning/scarring

Endotheliitis

Disciform keratitis = most common

Immune reaction causes stromal edema

Herpes Zoster Virus (HZV)

Varicella Zoster Virus (VZV) Older patients or immune

compromise Pre-zoster prodrome (fever,

malaise, tingling) Active zoster = skin

involvement respecting the vertical midline

Hutchinson’s sign = tip of nose

Peripheral Ulcerative Keratitis

Staph Marginal Keratitis

Type 3 hypersensitivity Sterile infiltrates where lid

touches cornea

Mooren’s Ulcer

Unilateral peripheral crescent-shaped ulcer

Corneal Deposits

Whorl Keratopathy Fleischer’s ring Rust rings Hudson-Stahli lines

Stocker’s line Ferry’s line Kayser-Fleischer Ring Band Keratopathy

Whorl Keratopathy

Caused by systemic disease or medication

No symptoms, no reduction in vision

Fleischer’s Ring

Keratoconus Iron ring at the base

of the con

Rust Rings

Form around metallic corneal foreign bodies

Must be removed along with foreign body

Hudson-Stahli Lines

Iron lines in lower cornea

No symptoms, no reduction in vision

Stocker’s Line

Iron deposit along edge of pterygium

Ferry’s Line

Iron deposits along edge of filtering bleb

Kayser-Fleischer Ring

Copper deposition around edges of cornea

Wilson’s disease (liver)

Band Keratopathy

Calcium deposition Bowman’s layer

Arcus Senilis

Corneal degeneration Most common peripheral

corneal opacity Older patient or high

cholesterol

Unilateral arcus indicates contralateral carotid disease

Corneal Graft Rejection

Type 4 Hypersensitivity

30% rejection rate in first year following transplant

Epithelial, stromal, or endothelial

Look for white blood cells

Refractive Surgery

Types

RK PRK CK Intact RLE PIOL AK

Contraindications

Age <18, unstable refraction

Keratoconus Active herpes/infection Connective tissue disease Immune compromise

(including diabetes) Large pupils

Radial Keratotomy (RK)

Radial incisions flatten the corneal stroma

Unstable Hyperopic shifts

Photorefractive Keratectomy (PRK)

Outer cornea removed (epithelium, Bowman’s, some stroma)

Less myopic because thinner cornea

No flap Healing: 1-2 weeks Problem: stromal haze

Laser-assisted In Situ Keratomileusis (LASIK)

Flap of cornea moved, laser applied beneath to thin stroma, then flap replaced

Less myopic because thinner cornea

Healing: 1-2 days Problem: dry eye

LASIK Complications

Initial pain Infection Flap complications Corneal ectasia

(thinning & protrusion, like keratoconus)

Residual refractive error (under-correction)

Glare Dry eye (#1) Epithelial ingrowth Corneal haze

Conductive Keratoplasty (CK)

Treats hyperopia & presbyopia

Shrink peripheral collagen fibers with radio energy

Problem: regression

Intacs (Intrastromal corneal rings)

PMMA ring in peripheral stroma

Used for keratoconus Less myopic because

ring flattens cornea Can be removed

Refractive Lens Extraction (RLE)

Remove natural crystalline lens, replace with new lens (like cataract surgery)

Works because lenses come in varying powers, select appropriate one

Phakic Intraocular Lens (PIOL)

Lens implanted into an eye in front of the iris (natural crystalline lens remains intact)

Great for high myopia Removable

Astigmatic Keratotomy (AK)

Blade incisions relax the steeper meridian of the cornea

Contact Lens-Related Disorders

Solution hypersensitivity/toxicity

Corneal neovascularization

Corneal warpage

Contact lens deposits Superior epithelial

arcuate lesion (SEAL)

Solution Hypersensitivity/Toxicity

Diffuse SPK (superficial punctate keratitis)

Corneal Neovascularization

Due to lack of oxygen (hypoxia)

If it’s >1.5mm, switch contact lenses or stop wearing them

Corneal Warpage

Cornea changes shape due to contact lenses

GP lenses (gas permeable, “hard” lenses)

Contact Lens Deposits

Deposits of tear components on contact lenses

Clean lenses better!

Dimple Veiling

Air bubbles trapped under a GP contact lens create divots in the cornea