Circumscribed posterior keratoconus

Posterior keratoconus is characterized by an internal protrusion of the posterior corneal surface and associated localized or diffuse stromal thinning. Two cases of circumscribed (localized) posterior keratoconus are presented that are representative of the spectrum of the anomaly.

The clinical and histological appearance of posterior keratoconus and its differential diagnosis from other corneal ectasias and developmental anomalies are reviewed to enable the eye care practitioner to better diagnose and manage this rare anterior segment disorder.