<unk>  <unk> , is a degenerative corneal condition, often confused with keratoconus. It typically presents with painless vision loss affecting both eyes. Rarely, it may cause acute vision loss with severe pain due to perforation of the cornea. It is typically characterized by a clear, bilateral thinning (ectasia) in the inferior and peripheral region of the cornea, although some cases affect only one eye. The cause of the disease remains unclear.<unk>  is diagnosed by corneal topography. Corneal pachymetry may be useful in confirming the diagnosis. Treatment usually consists of vision correction with eyeglasses or contact lenses. Intacs implants, corneal collagen cross-linking, and corneal transplant surgery are additional options. Surgery is reserved for individuals who do not tolerate contact lenses. The term<unk> " was first coined in 1957 by the ophthalmologist Schalaeppi. The word<unk> " means clear, indicating that the corneas retain clarity in<unk> . The condition is rare, though the exact prevalence and incidence are unknown.
Pellucid marginal degeneration
Keratoconus
Optic disc drusen
Posterior cortical atrophy
Vitreomacular adhesion
Geographic atrophy
Enlarged vestibular aqueduct
Choroidal neovascularization