Corneal ectatic disorders or corneal ectasia are a group of uncommon, noninflammatory, eye disorders characterised by bilateral thinning of the central, paracentral, or peripheral cornea.^[1]

Types

• Keratoconus, a progressive, noninflammatory, bilateral, asymmetric disease, characterized by paraxial stromal thinning and weakening that leads to corneal surface distortion.^[2]
• Keratoglobus, a rare noninflammatory corneal thinning disorder, characterised by generalised thinning and globular protrusion of the cornea.^[3]
• Pellucid marginal degeneration, a bilateral, noninflammatory disorder, characterized by a peripheral band of thinning of the inferior cornea.^[4]
• Posterior keratoconus, a rare condition, usually congenital, which causes a nonprogressive thinning of the inner surface of the cornea, while the curvature of the anterior surface remains normal. Usually only a single eye is affected.
• Post-LASIK ectasia, a complication of LASIK eye surgery.^[5]
• Terrien's marginal degeneration, a painless, noninflammatory, unilateral or asymmetrically bilateral, slowly progressive thinning of the peripheral corneal stroma.^[6]

Diagnosis

Usually diagnosed clinically by several clinical tests. Although some investigations might needed for confirming the diagnosis and to differentiate different types of corneal ectatic diseases.^{[citation needed]}

• Corneal topography
• Corneal tomography

Treatment

Treatment options include contact lenses and intrastromal corneal ring segments for correcting refractive errors caused by irregular corneal surface,^[7][8] corneal collagen cross-linking to strengthen a weak and ectatic cornea,^[9] or corneal transplant for advanced cases.