Fatty degeneration (Lipoid keratopathy)
Fatty degeneration of cornea is characterised by whitish or yellowish deposits. The fat deposits mostly consist of cholesterol and fatty acids. Initially fat deposits are intracellular but some become extracellular with necrosis of stromal
cells. Lipid keratopathy can be primary or secondary.
Fatty degeneration of cornea is characterised by whitish or yellowish deposits. The fat deposits mostly consist of cholesterol and fatty acids. Initially fat deposits are intracellular but some become extracellular with necrosis of stromal
cells. Lipid keratopathy can be primary or secondary.
- 1. Primary lipid keratopathy is a rare condition which occurs in a cornea free of vascularization. Serum lipid levels are normal in such patients.
- 2. Secondary lipid keratopathy occurs in vascularised corneas secondary to diseases such as corneal infections, interstitial keratitis, ocular trauma, glaucoma, and chronic iridocyclitis.
Treatment is usually unsatisfactory. In some cases slow resorption of lipid infiltrate can be induced by argon laser photocoagulation of the new blood
vessels.
Hyaline degeneration
Hyaline degeneration of cornea is characterised by deposition of hyaline spherules in the superficial stroma and can be primary or secondary.
1. Primary hyaline degeneration is bilateral and noted in association with granular dystrophy
2. Secondary hyaline degeneration is unilateral and associated with various types of corneal diseases including old keratitis, long-standing glaucoma,
trachomatous pannus. It may be complicated by recurrent corneal erosions.
Treatment of the condition when it causes visual disturbance is keratoplasty.
Amyloid degeneration
Amyloid degeneration of cornea is characterised by deposition of amyloid material underneath its epithelium. It is very rare condition and occurs in
primary (in a healthy cornea) and secondary forms (in a diseased cornea).
Calcific degeneration (Band Shape keratopathy)
Band shape keratopathy (BSK) is essentially a degenerative change associated with deposition of calcium salts in Bowman's membrane, most superficial
part of stroma and in deeper layers of epithelium.
vessels.
Hyaline degeneration
Hyaline degeneration of cornea is characterised by deposition of hyaline spherules in the superficial stroma and can be primary or secondary.
1. Primary hyaline degeneration is bilateral and noted in association with granular dystrophy
2. Secondary hyaline degeneration is unilateral and associated with various types of corneal diseases including old keratitis, long-standing glaucoma,
trachomatous pannus. It may be complicated by recurrent corneal erosions.
Treatment of the condition when it causes visual disturbance is keratoplasty.
Amyloid degeneration of cornea is characterised by deposition of amyloid material underneath its epithelium. It is very rare condition and occurs in
primary (in a healthy cornea) and secondary forms (in a diseased cornea).
Calcific degeneration (Band Shape keratopathy)
Band shape keratopathy (BSK) is essentially a degenerative change associated with deposition of calcium salts in Bowman's membrane, most superficial
part of stroma and in deeper layers of epithelium.
Etiology
- Ocular diseases. Band keratopathy is seen in association with: chronic uveitis in adults, children with Still's disease, phthisis bulbi, chronic glaucoma, chronic keratitis and ocular trauma.
- Age related BSK is common and affects otherwise healthy cornea.
- Metabolic conditions rarely associated with BSK include hypercalcaemia and chronic renal failure.
Clinical features. It typically presents as a bandshaped opacity in the interpalpebral zone with a clear interval between the ends of the band and the limbus (Fig. 1). The condition begins at the periphery and gradually progresses towards the centre. The opacity is beneath the epithelium which usually remains intact. Surface of this opaque band is stippled due to holes in the calcium plaques in the area of nerve canals of Bowman's membrane. In later stages, transparent clefts due to cracks or tears in the calcium plaques may also be seen.
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| Fig.1. Band-shaped keratopathy in a patient with chronic uveitis. |
Treatment. It consists of :
1. Chelation, i.e., chemical removal of deposited calcium salts is an effective treatment. First of all corneal epithelium is scraped under local anaesthesia. Then 0.01 molar solution of EDTA (chelating agent) is applied to the denuded cornea with the help of a cotton swab for about 10 minutes. This removes most of the deposited calcium. Pad and bandage is then applied for 2- 3 days to allow the epithelium to regenerate.
2. Phototherapeutic keratectomy (PTK) with excimer laser is very effective in clearing the cornea.
3. Keratoplasty may be performed when the band keratopathy is obscuring useful vision.
3. Keratoplasty may be performed when the band keratopathy is obscuring useful vision.
Salzmann's nodular degeneration
Etiology. This condition occurs in eyes with recurrent attacks of phlyctenular keratitis, rosacea keratitis and trachoma. The condition occurs more commonly in women and is usually unilateral.
Pathogenesis. In Salzmann's nodular degeneration, raised hyaline plaques are deposited between epithelium and Bowman's membrane. There is associated destruction of Bowman's membrane and the adjacent stroma.
Clinical features. Clinically, one to ten bluish white elevations (nodules), arranged in a circular fashion, are seen within the cornea. Patient may experience discomfort due to loss of epithelium from the surface of nodules. Visual loss occurs when nodules impinge on the central zone.
Treatment is essentially by keratoplasty.
Etiology. This condition occurs in eyes with recurrent attacks of phlyctenular keratitis, rosacea keratitis and trachoma. The condition occurs more commonly in women and is usually unilateral.
Pathogenesis. In Salzmann's nodular degeneration, raised hyaline plaques are deposited between epithelium and Bowman's membrane. There is associated destruction of Bowman's membrane and the adjacent stroma.
Clinical features. Clinically, one to ten bluish white elevations (nodules), arranged in a circular fashion, are seen within the cornea. Patient may experience discomfort due to loss of epithelium from the surface of nodules. Visual loss occurs when nodules impinge on the central zone.
Treatment is essentially by keratoplasty.
Furrow degeneration (Senile marginal degeneration)
In this condition thinning occurs at the periphery of cornea leading to formation of a furrow. In the presence of arcus senilis, the furrow occupies the area of lucid interval of Vogt. Thinning occurs due to fibrillar degeneration of the stroma. Patient develops defective vision due to induced astigmatism.
Treatment is usually not necessary.
Spheroid degeneration
(Climatic droplet keratopathy/Labrador keratopathy/ Bietti's nodular dystrophy)/corneal elastosis.
Etiology. It typically occurs in men who work outdoors, especially in hostile climates. Its occurrence has been related to exposure to ultraviolet rays and/ or ageing and /or corneal disease.
Clinical features. In this condition amber-coloured spheroidal granules (small droplets) accumulate at the level of Bowman's membrane and anterior stroma
in the interpalpebral zone. In marked degeneration, the vision is affected.
In this condition thinning occurs at the periphery of cornea leading to formation of a furrow. In the presence of arcus senilis, the furrow occupies the area of lucid interval of Vogt. Thinning occurs due to fibrillar degeneration of the stroma. Patient develops defective vision due to induced astigmatism.
Treatment is usually not necessary.
Spheroid degeneration
(Climatic droplet keratopathy/Labrador keratopathy/ Bietti's nodular dystrophy)/corneal elastosis.
Etiology. It typically occurs in men who work outdoors, especially in hostile climates. Its occurrence has been related to exposure to ultraviolet rays and/ or ageing and /or corneal disease.
Clinical features. In this condition amber-coloured spheroidal granules (small droplets) accumulate at the level of Bowman's membrane and anterior stroma
in the interpalpebral zone. In marked degeneration, the vision is affected.
Pellucid marginal degeneration
It is characterised by corneal thinning involving the periphery of lower cornea. It induces marked astigmatism which is corrected by scleral type contact lenses.
Terrien's marginal degeneration
Terrien's marginal degeneration is non-ulcerative thinning of the marginal cornea.
Clinical features are as follows :
1. Predominantly affects males usually after 40 years of age.
2. Mostly involves superior peripheral cornea.
3. Initial lesion is asymptomatic corneal opacification separated from limbus by a clear zone.
4. The lesion progresses very slowly over many years with thinning and superficial vascularization. Dense yellowish white deposits may be seen at
the sharp leading edge. Patient experiences irritation and defective vision (due to astigmatism).
Complications such as perforation (due to mild trauma) and pseudopterygia may develop.
Treatment is non-specific. In severe thinning, a patch
of corneal graft may be required.
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