METABOLIC AND DEGENERATIVE DISEASE

Junctional: along BM; may rarely have malignant transformation.

Compound: junctional and stromal; have cystic inclusions in epithelium and are never malignant.

Subepithelial: in stroma; no malignant potential.

MALIGNANT MELANOMA, CONJUNCTIVAL Arises from PAM (30%), nevus (40%), or de novo (30%) in mature adults and violates the BM. Thirty percent mortality overall, with metastases to regional lymph nodes or orbital extension. On pathology, does not have spindle A or B cells like uveal melanoma (which metastasizes preferentially to the liver and has 50% mortality). If multicentric, consider that this may be metastatic MM to the conjunctiva.

Breslow thickness is prognostic: depth of invasion >0.8 mm has worst prognosis. Pedunculated lesion has better prognosis, amelanotic worst. HMB-45 marker is (þ) in 50%; also may be S-100 (þ) (as with neural crest cells).

Excise lesion and cryotherapy; if recurrent (usually amelanotic), consider enucleation.

OCULAR MELANOCYTOSIS Typically affects Asian or African-American patients with focal melanocyte proliferation (blue nevus); half have ipsilateral skin pigmentation (Ota’s nevus); increased uveal and orbital melanoma risk.

PRIMARY ACQUIRED MELANOSIS (PAM) Acquired unilateral conjunctival pigmentation in middle-aged Caucasian patients that waxes and wanes. Pathology demonstrates increased number of melanocytes confined to the basal epithelium. Different from nevi, which are larger, more diffuse, and approach the limbus. Do three incisional biopsies (one at the most elevated area, one at the transition area, and one at a random or limbal area). Melanoma is present in 32% of cases. Excise and cryotherapy entire area. Prognosis depends on whether cellular atypia is present on pathology:

Thirty-three percent of cases are without atypia: 0% melanoma risk, just increased number of melanocytes.

Sixty-seven percent of cases are with atypia: 46% melanoma risk, lower risk if pathology shows basilar hyperplasia. Is basically MM confined to basal layer.

Metabolic and Degenerative Disease

BAND KERATOPATHY Calcification of Bowman’s layer, typically in sick eyes (leading cause is chronic uveitis or glaucoma) or from systemic chronic mercurial exposure, hypercalcemia or hyperphosphatemia (milk-alkali syndrome), kidney or liver disease. Has ‘‘Swiss cheese’’ appearance. Called

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122 CORNEA AND CONJUNCTIVA

‘‘calcerous degeneration’’ if exaggerated band keratopathy. Check Caþ, phosphorus, and uric acid levels if no obvious cause. Treat symptoms with BSCL, ethylenediaminetetraacetic acid (EDTA) chelation (0.08–0.25 mol/ L or a 1.5–3.0% solution), superficial keratectomy, or PTK.

COAT’S WHITE RING From foreign body breakdown.

CORNEAL ARCUS Rule out hyperlipdemia if <40 years old (arcus juvenilus); has lucid zone, starts inferiorly. If arcus is asymmetric, rule out contralateral carotid artery stenosis.

CORNEAL FARINATA Seen in older patients with ‘‘flour dust’’ flecks in deep stroma; not visually significant.

CROCODILE SHAGREEN Polygonal faint gray opacities with clear borders. If anterior, also known as mosaic degeneration; if posterior, is associated with central cloudy Franc¸ois’ dystrophy.

FLOPPY EYELID SYNDROME Spontaneous upper lid eversion during sleep, often in obese patients. Associated with obstructive sleep apnea and decreased rapid eye movements (REM) sleep. Conjunctival inflammation is driven by hypoxia plus mechanical trauma and shows a fine velvety tarsal reaction. Treat with a nocturnal shield for 1 month, lid shortening procedure, or topical retinoic acid 0.01% to decrease lid keratinization.

HASSALL-HENLE BODIES Benign, age-related peripheral guttae, not a disease.

IRIDOCORNEAL ENDOTHELIAL (ICE) SYNDROME Acquired, nonfamilial, unilateral disease of epithelialized endothelium (hammered-metal appearance) that migrates across the posterior cornea, trabecular meshwork, and iris. Usually occurs in middle-aged females with a high incidence of glaucoma. May be related to PPMD, which is a bilateral inherited disorder of epithelialized endothelium; others have suggested a possible HSV etiology. Differential diagnosis: PPMD, Fuchs’ endothelial dystrophy, Axenfeld-Rieger syndrome, aniridia, iridoschisis, iris nevus syndrome, iris melanoma, and NF. Treat edema with dehydration. If glaucoma is present, treat IOP; patients usually do well with trabeculectomy (if closed, may need to YAG laser trabeculectomy opening) but not argon laser trabeculoplasty (ALT). May need PK for corneal edema, but do not allow AC to become shallow, as iris sticks to endothelium. ICE syndrome is a spectrum of diseases (mnemonic: ICE):

Iris nevus (Cogan-Reese syndrome): advanced ICE with pigmented iris nodules (not true nevi, but mamillations of iris pinched up in the membrane), iris atrophy, and pupillary distortion.

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Chandler’s syndrome: 56% of patients have signs confined mainly to the cornea, with edema and less prominent iris findings. Presents with pupil abnormality, decreased VA, or pain (corneal edema). May have subclinical mild pleomorphism in fellow eye. Gonioscopy shows broad PAS and a cellular membrane.

Essential iris atrophy: progression from Chandler’s syndrome as the abnormal endothelium moves onto the iris, causing atrophy (stretch holes from membrane away from the PAS or ischemic melting holes in the area of the PAS), corectropia, and polycoria. More likely to have glaucoma at this stage.

KELOID More glistening and jellylike than a dermoid

LABRADOR OR SPHEROIDAL DEGENERATION, CLIMATIC DROPLET, OR RICE PADDY KERATOPATHY Solar elastosis with proteinaceous deposits in the superficial cornea; a pinguecula, or yellowish spot of proliferation, of the cornea, with pannus and band keratopathy. Usually bilateral, M > F.

LIMBAL VOGT’S GIRDLE Pinguecula of the cornea

LIPID KERATOPATHY Vascularized corneal scars (as from HSV) allow lipid to deposit. May attempt to close vessel with argon laser.

PINGUECULA Yellow, gray conjunctival thickening from UV damage. Pathology shows solar elastosis (fragmented and ‘‘cooked’’ subepithelial connective tissue), as seen in actinic keratosis. Verhoeff-von Gieson stain shows elastoid degeneration.

PTERYGIUM (from the Greek pterygion, ‘‘wing’’) A triangular fibrovascular growth onto the cornea, usually nasal, bilateral, and progressive. May cause astigmatism, irritation, and EOM restriction. Cannot pass a muscle hook underneath if at the limbus, unlike a pseudopterygium, which can occur after trauma. Pterygium and SCC incidence increase near equatorial climates and usually are interpalpebral (if not, think SCC).

Etiology is the same as pinguecula. In addition, focal limbal stem cell deficiency is caused by the natural ‘‘hot spot’’ of UV light directed temporally across the cornea. This preferentially focuses light onto the nasal limbus, damaging the basal limbal cells that are otherwise protected from direct head-on light by the overlying epithelium. This allows secondary conjunctivalization, seen as a pterygium.

Pathology shows elastoid degeneration (stains with elastin but does not digest with elastase). ‘‘Recurrent’’ pterygium is pyogenic tissue.

Treatment: bare sclera excision has 30 to 70% recurrence; excision with primary closure (pedicle flap), 5 to 10% recurrence; with conjunctival autograft or with mitomycin, 5% recurrence.

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124 CORNEA AND CONJUNCTIVA

SALZMANN’S NODULES Gray-white elevated lumps composed of hyaline on Bowman’s layer, usually seen in older female patients. Most arise from sequelae to staphylococcal lid disease, old keratitis, or trauma. Treat with superficial keretectomy (‘‘SuperK’’) by lifting with 0.12 forceps, and peel or scrape with Weck-Cel sponge or #15 blade or PTK.

VITAMIN A DEFICIENCY More severe ocular scarring if it coincides with measles infection. Causes decreased goblet cells, drying, and keratinization of conjunctiva (Bitot’s spots) that are foamy from Corynebacterium, corneal scar, and central leukoma. Contributes to the cause of 70% of childhood blindness; also have nyctalopia.

DEGENERATIONS: ECTATIC CORNEAL DISORDERS

Fuchs’ marginal keratolysis: upside down Terrien’s marginal degeneration (inferior location).

Furrow degeneration: benign corneal thinning that is more apparent than real.

Keratoconus: acquired, bilateral (often asymmetric), noninflammatory anterior ectasia. Onset after puberty, M:F ¼ 2:1; slowly progressive for 5 to 10 years, then stable (later onset has a better prognosis). Familial pattern exists but no clear inheritance pattern; family members may have subclinical inferior steepening.

Many associated conditions: Down syndrome (eye rubbing is likely cause, as increased incidence of OD keratoconus with right-handed individuals and vice versa), atopy, RP, Leber’s congenital amaurosis, osteogenesis imperfecta, Ehlers-Danlos syndrome, Marfan syndrome, Alport’s syndrome, mitral valve prolapse, and keratosis palmaris and plantaris.

Ectasia causes irregular astigmatism and myopia. Clinical signs include outward lower lid bulge with downgaze (Munson’s sign), shadow with tangential light illumination (Rizutti’s sign), inferotemporal corneal thinning, deep vertical scars (Vogt’s striae), epithelial iron ring around base of cone (Fleischer ring), and scissoring on retinoscopy. Acute edema or hydrops (break in Descemet’s membrane) often resolves spontaneously after 4 to 6 weeks with scarring; degenerative pannus between Bowman’s layer and epithelium may develop, and apical scarring may be nodular (easily removed with superficial keratectomy) or diffuse (needs PK).

Treat with spectacles, then RGP, for irregular astigmatism (fit to vault apex; may need to piggyback lenses); 90% of patients never need surgery. PK is more than 95% successful (may have persistent mydriasis after PK). Keratoconus is a contraindication to refractive surgery.

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Keratoglobus: rare nonhereditary globular rather than conical midperipheral thinning from defect in collagen synthesis. Present from birth; high myopia with K readings 55–60 D, and risk of spontaneous rupture, so prescribe safety lenses. PK is difficult.

Pellucid marginal degeneration: noninflammatory, bilateral, peripheral thinning, usually inferior location. Usually seen in 20to 40-year-old patients of European or Japanese descent, M ¼ F. Causes irregular against-the-rule (ATR) astigmatism. Can be considered as keratoconus near the limbus, with a thinned inferior band 1–2 mm wide and corneal bulging superior to thinned area. May have hydrops, but no lipid or vascularization. Prescribe eye protection and RGP lenses, and consider annular lamellar keratectomy.

Terrien’s marginal degeneration: peripheral corneal thinning that begins superiorly (mnemonic: Terrien’s on top, pellucid on bottom), then moves circumferentially, causing bilateral corneal steeping at 90 degrees (ATR astigmatism). Intact epithelium and usually noninflammatory quiet eye (unlike Mooren’s ulcer). Usually patients are 20 to 30 years old, M > F. Typically static, with lipid deposition and fine vascular pannus, but may be inflammatory and progressive. Associated with pseudopterygium (can pass muscle hook under it, unlike a pterygium). May perforate with trauma. Treat with corneal allograft or compression sutures over thinned area (tighten to make with-the-rule astigmatism equal to amount of previous ATR astigmatism, and cut sutures over several months to regress to middle).

DEGENERATIONS: METABOLIC DEPOSITIONS

Amyloidosis: eosinophilic hyaline material deposited in various tissues that represents chondroitin/sulfuric acid protein in a beta-pleated sheet that the body cannot degrade. At least 14 genes are involved in amyloidosis, with 3 identified types: AP if derived from alpha globulin, AL if composed of immunoglobulin, and AA for nonimmunoglobulin.

Characteristics (mnemonic: ABCDEF):

Autoflouresence

Birefringent: two polarizing filters block all light except that which is phase-shifted by amyloid.

Congo-philia: stains with Congo red, and also metachromatically with crystal violet and thioflavin T.

Dichroism: changes from red to green with a filter and green light; all the tissue looks red except the Congo red–stained amyloid, which has parallel light rays and looks green.

Electron microscopic bundles of microfilaments

Filaments

Four clinical classifications:

Primary localized amyloidosis: most common type, characterized by conjunctival plaques. Most are nonfamilial but are

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