Micropannus

Synonyms

Corneal neovascularization; Corneal vascularization

Definition

Micropannus is a form of subepithelial corneal fibrovascular proliferation, which extends beyond the normal vascular arcade at the limbus. Micropannus is differentiated from gross pannus in that its extension is less than 2 mm beyond the vascular arcade, while gross pannus goes beyond 2 mm. Micropannus is associated with many ocular surface disorders and can progress to frank scarring of the ocular surface as well as gross corneal neovascularization (NV). In rare instances it can progress to deep corneal neovascularization affecting the deeper stromal layers of the cornea.

Etiology

Micropannus generally develops as a result of four main processes:

• 1. Hypoxia. This is most commonly associated with extended contact lens wear, especially softgel contact lenses worn during sleep, as the lens and closed eyelid generate a barrier to corneal oxygenation. The development of neovascularization in this circumstance is an...