Pellucid marginal degeneration

Terrien's marginal degeneration, also known as Terrien's corneal marginal degeneration, is a degenerative condition of the corneal periphery characterized by thinning and ectasia of the corneal margin. The disease course is prolonged and progresses slowly, sometimes lasting 20 years or more. This condition is common in young adults. Early stages are asymptomatic. Late stages are primarily characterized by slow, progressive vision loss that cannot be corrected with glasses.