Terrien marginal degeneration

A rare disorder of the anterior segment of the eye characterized by slowly progressive, bilateral, asymmetric, usually non-inflammatory degeneration of the peripheral cornea, resulting in stromal thinning, vascularization, lipid deposition, and against-the-rule astigmatism with decreased visual acuity. Degeneration typically involves the superior aspect of the cornea first and extends circumferentially, leading to circumferential ectasia of the peripheral cornea. Opacification of the central cornea may occur at a very advanced stage. In rare cases, the condition is complicated by perforation.