# Corneal Dystrophies and Degenerations

> Corneal dystrophies and degenerations for MBBS Ophthalmology: granular, lattice, macular, Fuchs guttata, band keratopathy, arcus and Mooren ulcer.

- Canonical URL: https://prepelephant.com/topics/mbbs/ophthalmology/corneal-dystrophies-and-degenerations
- Exam / course: MBBS · Subject: Ophthalmology
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Corneal Dystrophies and Degenerations", PrepElephant, https://prepelephant.com/topics/mbbs/ophthalmology/corneal-dystrophies-and-degenerations

## Direct answer

Corneal dystrophies are bilateral, hereditary, non-inflammatory, progressive conditions that typically affect the central cornea without vascularisation, whereas degenerations are unilateral or asymmetric, age-related or secondary changes, often peripheral and linked to environmental or systemic causes. The examinable stromal trio — granular dystrophy (autosomal dominant, hyaline deposits staining with Masson trichrome), lattice dystrophy (autosomal dominant, amyloid staining with Congo red showing apple-green birefringence) and macular dystrophy (autosomal recessive, mucopolysaccharide staining with Alcian blue, the least common but most visually disabling) — sits beside anterior dystrophies such as map-dot-fingerprint disease and endothelial Fuchs dystrophy with its corneal guttata. Among degenerations, arcus senilis, band-shaped keratopathy, spheroidal degeneration and Terrien marginal degeneration carry the examinable systemic and treatment links.

## What you must remember

- **The dystrophy definition (five words examiners want):** bilateral, hereditary, non-inflammatory, central, progressive — and avascular; fail any one of these and the lesion is usually a degeneration.
- **Granular dystrophy (Groenouw type I):** autosomal dominant, discrete white "breadcrumb" or crushed-glass opacities separated by clear stroma in the central cornea, sparing the periphery; deposits are hyaline (Masson trichrome positive); TGFBI gene related; relatively good vision until late.
- **Lattice dystrophy:** autosomal dominant, branching refractile lattice lines plus subtle stromal haze, amyloid on Congo red with apple-green birefringence under polarised light; recurrent corneal erosion is the presenting problem; systemic amyloidosis accompanies the rarer gelsolin-related (Meretoja) variant.
- **Macular dystrophy (Groenouw type II):** autosomal recessive — the exception among the trio — diffuse stromal haze with localised grey opacities reaching the periphery and the limbus, caused by mucopolysaccharide (glycosaminoglycan) deposition (Alcian blue positive); earliest and most severe visual loss, frequently needing keratoplasty by young adulthood.
- **Epithelial basement membrane dystrophy (map-dot-fingerprint, Cogan microcystic):** the commonest anterior dystrophy and the leading cause of recurrent corneal erosion; treated with lubricants, hypertonic saline and bandage contact lens.
- **Fuchs endothelial dystrophy:** corneal guttata (excrescences of Descemet membrane) with a beaten-metal appearance, later stromal and epithelial oedema with morning blur, accelerated by cataract surgery; treated by endothelial keratoplasty (DSAEK or DMEK).
- **Degenerations with exam hooks:** arcus senilis is a peripheral lipid ring in the elderly, and its appearance under 40 (arcus juvenilis) warrants a lipid profile; band-shaped keratopathy is calcific interpalpebral opacity linked to chronic uveitis or hypercalcaemia, treated by EDTA chelation; spheroidal degeneration is UV-linked; Terrien marginal degeneration is painless peripheral thinning.
- **Two ulcerative degenerations to separate:** Mooren ulcer is a painful, progressive peripheral ulcerative keratitis with an overhanging central edge, treated with steroids and immunosuppression; rheumatoid and infective peripheral keratitis must be excluded first.

## How to work through three white corneas in one clinic

Three patients, three mechanisms, three management lines. A 35-year-old with breadcrumbs of white in the central cornea of both eyes, clear periphery, vision 6/9: granular dystrophy — confirm the pedigree, reassure about slow progression; if the visual axis opacifies, lamellar keratoplasty restores it, though dystrophies can recur in the graft. The second, a 28-year-old with recurrent painful morning watering and sticky lids, shows branching refractile lines: lattice — manage the erosions (lubricants, hypertonic saline, bandage lens) and explain that amyloid, not infection, causes the picture. The third, a 20-year-old with dense central haze reducing vision to 6/36 and opacities that reach the limbus: macular — the recessive one, the severe one, and the one already needing keratoplasty; counsel the family on recessive inheritance and screen siblings. What changes across the three is only the deposit chemistry and tempo: the examinable stains — trichrome, Congo red, Alcian blue — map to the three in that order, a mapping Indian university papers ask every few years.

## Where students slip

The first slip is calling a peripheral, unilateral, vascularised opacity in an elderly farmer a "dystrophy" — degenerations own those adjectives, dystrophies surrender them. The second is the inheritance mix-up: macular dystrophy is the autosomal recessive outlier, granular and lattice are dominant, and reversing this in a viva costs the whole question. Third, band-shaped keratopathy is not a stromal dystrophy but a calcific degeneration in the exposed interpalpebral strip — its associations (chronic uveitis, hypercalcaemia, renal failure) and its treatment by EDTA chelation are the marks. Finally, remember that Fuchs dystrophy decompensates after routine cataract surgery — the "healthy" cornea with guttata and thickened pachymetry needs protective, sometimes combined endothelial surgery, a decision made before the phaco, not after.

## Frequently asked questions

### How do corneal dystrophies differ from degenerations?

Dystrophies are bilateral, hereditary, non-inflammatory, centrally located, progressive and avascular; degenerations are age-related or secondary, often unilateral or asymmetric, frequently peripheral, and may show vascularisation.

### Which stains identify the three classic stromal dystrophies?

Granular — hyaline, Masson trichrome; lattice — amyloid, Congo red with apple-green birefringence; macular — mucopolysaccharide, Alcian blue.

### Which stromal dystrophy is autosomal recessive and most visually severe?

Macular dystrophy (Groenouw type II), with diffuse glycosaminoglycan deposition extending to the periphery and keratoplasty often needed by early adulthood.

### What is the significance of arcus senilis appearing under age 40?

Termed arcus juvenilis, it warrants a fasting lipid profile — it may signal hyperlipidaemia and premature atherosclerotic risk.

### How is band-shaped keratopathy treated?

By chelation with disodium EDTA after epithelial debridement, plus management of the underlying cause — chronic uveitis, hypercalcaemia or renal failure.