Congenital Abnormalities of the Cornea
Ophthalmology High-Yield Essentials
1. Key Developmental Anomalies
| Condition | Clinical Presentation |
|---|---|
| Megalocornea | Corneal diameter > 13 mm in a non-glaucomatous eye. Usually X-linked recessive. |
| Microcornea | Corneal diameter < 10 mm. Often associated with hyperopia and glaucoma. |
| Cornea Plana | Flat cornea (low keratometry readings). Often associated with sclerocornea. |
| Sclerocornea | The peripheral cornea resembles sclera (non-transparent). Can be bilateral. |
2. Important Syndromic Associations
- Peters Anomaly: Central corneal opacity with an iris adhesion (iridocorneal adhesion). It is a form of anterior segment dysgenesis.
- Posterior Keratoconus: Rare, non-progressive central posterior corneal indentation.
- Axenfeld-Rieger Syndrome: Iris anomalies, corneal ectasia, and peripheral anterior synechiae associated with glaucoma risk.
3. NEET PG High-Yield Pearls
- Megalocornea vs. Buphthalmos: Megalocornea has normal intraocular pressure (IOP); Buphthalmos (congenital glaucoma) presents with high IOP, Haab’s striae, and optic disc cupping.
- Haab’s Striae: Breaks in the Descemet’s membrane caused by stretching of the eyeball in congenital glaucoma.
- Cornea Plana: Associated with hyperopia and a higher risk of angle-closure glaucoma due to shallow anterior chambers.