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34 Cards in this Set
- Front
- Back
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What are some corneal dystrophies? |
The most common ones are: • Epithelial basement membrane dystrophy • Reis-Buckler dystrophy • Lattice degeneration • Granular dystrophy • Keratoconus (ectatic) • Keratoglobus (ectatic) |
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Describe Epithelial basement membrane dystrophy (EBM) |
• The most common corneal dystrophy • Bilateral, asymmetrical • AKA map/dot/fingerprint dystrophy or Cogan’s microcystic dystrophy |
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What are the symptoms of EBM? |
Often symptomless, hence the optometrist is the first to find signs• 10% give recurrent corneal epithelial erosions (RCEE) >age 30; -> sharp pain on waking and blurred vision • Rare blurred vision with RCEE • Most notice fluctuating vision |
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What are the signs of EBM? |
• Typically first noticed after age 30 • Epithelial microcysts in inferior cornea • Dots • Fingerprints • Maps |
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What is the pathophysiology of EBM? |
• Basal cells in corneal epithelium develop finger-like projections that prevent adherence of the overlying epithelial cells • Trapped cells and debris form microcysts • Larger areas of trapped cells and debris under Bowman’s, which is regenerating, form dots • Fingerprints – folds in Bowman’s as it regrows • Maps – anterior stromal and Bowman’s change in collagen organisation to give large, irregularly shaped, hard edged areas of corneal scatter |
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What is the management of EBM? |
• RCEE treated with overnight ointment for corneal lubrication • Bandage lenses are sometimes used • Superficial Phototherapeutic keratectomy may be used to manage the RCEE • Screen family members |
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What is Reis-Buckler dystrophy (R-B)? |
• Bilateral, symmetric, AD inherited, high penetrance, variable expression • Much less common than EBM dystrophy • Starts in childhood as RCEE, gradually developing |
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What are the symptoms of Reis-Buckler dystrophy (R-B)? |
• Red eyes with sharp pain on waking • FH+, but variable effects • Blurred vision in later stages due to corneal scarring • Later loss of corneal sensation |
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What are the signs of Reis-Buckler dystrophy (R-B)? |
• RCEE (late childhood) • Honeycomb of greyish opacities seen in the epithelium, principally centrally (first decade) • Densest opacities in mid-periphery. The outer 1-2mm are spared |
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What is the pathophysiology of R-B? |
• Bowman’s layer is replaced with irregular bands of collagen • Epithelial pits and heaps result in a visible lattice pattern, reducing vision and allowing epithelial to be lost easily (RCEE) • The abnormality eventually penetrates into the stroma and scarring produced corneal hypothaesia |
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What is the management of R-B? |
• Genetic counselling • RCEE management as for EBM dystrophy • Superficial keratectomy by 5th decade • Or PTK (but induces hypermetropia and corneal haze) |
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Describe lattice dystrophy (LD)? |
• Bilateral, symmetric, AD inherited, high penetrance • Very rare • Affects anterior stroma • Type 1 starts in first decade, with severe effects • Type 2 starts in middle age with moderate effects |
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What are the symptoms of lattice degeneration? |
• FH+ • RCEE Sx • Blurred vision |
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What are the signs of lattice degeneration? |
• Fine translucent, criss-cross lines in anterior stroma of central cornea • Progress to opacify the spaces between lines and extend to peripheral cornea and deeper stroma • Epithelial cell loss over the lines • Facial palsy in type 2 |
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What is the pathophysiology of LD? |
• Amyloid tissue (an insoluble protein) is laid down in anterior stroma • This disorders stromal fibres and leads to opacification • Epithelial cells cannot adhere to the disturbed stromal tissue and form RCEE |
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What is the management for LD? |
• Genetic counselling • As for RCEE in EMB and R-B dystrophy • Type 1 eventually (middle age) requires lamellar or penetrating keratoplasty • Following this, recurrence occurs, but slowly and concentrated in the peripheral cornea |
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What are the associated conditions of lattice degeneration? |
• Systemic amyloidosis in type 2 |
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Describe granular dystrophy? |
• Bilateral, symmetric, AD inherited, high penetrance • Rare • Affects anterior stroma • Type 1 starts in first decade, with severe effects • Type 2 starts in middle age with moderate effects • Type 3 starts in later life |
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What are the symptoms of granular dystrophy? |
• FH+ • RCEE Symptoms for type 1 • Blurred vision as disease progresses |
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What are the signs of granular dystrophy? |
• Small crumb-like white opacities in anterior stroma of central cornea • The spaces between opacities remain clear, but the opacities grow over time, becoming deeper, spreading to the periphery and becoming confluent • Epithelial cell loss over the opacities |
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What is the pathophysiology of granular dystrophy? |
• Granular material from eosinophils (immune system cells) is laid down in anterior stroma • This disorders stromal fibres and leads to opacification • Epithelial cells cannot adhere to the disturbed stromal tissue and form RCEE |
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What is the management of GD? |
• Genetic counselling • As for RCEE in EMB, R-B and lattice dystrophy • Type 1 much less likely to require penetrating keratoplasty than LD • Type 2 and 3 effects tend to be mild |
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Describe keratoconus |
• Bilateral, asymmetrical, familial (AD, variable penetrance) • Prevalence 1/1000 (common for a dystrophy) • Prevalence is 1/10 in individuals with Down’s syndrome • Onset typically in early teens and stable by late twenties |
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What are the symptoms of keratoconus? |
• FH+ • Atopic disease • Down’s syndrome • Blurred vision • Glare |
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What are the signs (Ret, Rx, Keratometer, Topography) of keratoconus? |
• Scissors reflex, inferior shadow in reflex • High and rapidly increasing myopia • High and rapidly increasing astigmatism • Large, oblique, non-orthogonal, corneal cylinder • Reduced quality mires • Inferior and irregular corneal steepening • Reduced VA when corrected with spectacle • RGP VA > spectacle VA • Thinned cone of cornea centrally and inferiorly • Ectatic cone of cornea centrally and inferiorly • Posterior central vertical stromal striae (Vogt’s) • Bulging of lower lid on downgaze (Munson’s sign) • Brown ring around base of cone (Fleischer’s ring) • Anterior stromal scarring • Breaks in Descemet’s membrane and acute hydrops |
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What are the two types of ectatic dystrophy? |
• Keratoconus • Keratoglobus |
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What is the pathophysiology of keratoconus? |
• Unknown. Corneal repair mechanisms have been implicated • Principle adverse effect is corneal thinning leading to: • Irregular ectasia -> myopia and astigmatism • Stretching of anterior stroma and Vogt’s striae • Scarring • Stretching and breaking of Decemet’s membrane causing hydrops • Iron deposition around base of cone gives Fleischer’s ring |
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What is the management of keratoconus? |
• 1% risk of a child of a patient inheriting the condition without FH+ (RR=10x) • Regular spectacle Rx updates • RGP contact lenses • Avoid eye rubbing and corneal refractive surgery • Scleral contact lenses • Penetrating or deep lamellar keratoplasty (10-20%) |
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Describe keratoglobus |
• V rare, bilateral, symmetrical, AD, high penetrance • Usually slowly developing from birth • Thinning throughout cornea, unlike keratoconus, and maximal in mid-periphery (therefore no cone or ring) • Very deep AC • Management as for keratoconus, but more difficult |
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Describe cornea guttata |
• Cornea guttata is very commonly present in older eyes (70% of those over 40 years), though it is often overlooked. • There is no clear clinical distinction to be made between this condition, when advanced, and early Fuchs’ dystrophy • The posterior profile of the cornea is raised in multiple minute excrescences that, especially by indirect illumination, look slightly like raindrops (guttae in Latin) on a window pane |
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Describe Fuch’s dystrophy |
• Fuchs’ dystrophy usually behaves more like a degeneration than a dystrophy, being found mainly in the elderly, • AD inheritance Fuchs’ dystrophy patients found the condition in 38% of relatives aged over 40 years • There are associations with open angle glaucoma and with cataract. |
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What is clinical stage 1of Fuch’s dystrophy? |
Stage 1 • Asymptomatic • Central posterior cornea shows guttata changes and pigment dusting • Descemet’s membrane appears grey and thickened |
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What is clinical stage 2 of Fuch’s dystrophy? |
Stage 2 • Visual acuity drops, with diurnal variation (worst on waking) • Stromal oedema • Wrinkles in Descemet’s membrane • Epithelial oedema leading to bullous keratopathy and pain |
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What is clinical stage 3 of Fuch’s dystrophy? |
Stage 3 • Less pain as collagen is deposited deep in the epithelium • Vision drops further |
