Keratoconus

Keratoconus is an eye disorder in which the cornea, the transparent front part of the eye, gradually thins and bulges outward into a cone shape.^[4] This causes distorted vision, including blurry vision, double vision, increased nearsightedness, irregular astigmatism, and light sensitivity, which can reduce quality of life.^[4][5][6] Both eyes are usually affected.^[4]

The cause is not fully understood but likely involves a combination of genetic, environmental, and hormonal factors.^[4] Having a parent, sibling, or child with keratoconus increases risk significantly.^[7][8] Environmental risk factors include frequent eye rubbing and allergies.^[9] Diagnosis is typically made with corneal topography, which maps the shape of the cornea and reveals characteristic changes.^[4]

In early stages, vision is often corrected with glasses or soft contact lenses.^[4] As the condition progresses, rigid or scleral contact lenses may be needed.^[4] In 2016, the FDA approved corneal collagen cross-linking to halt progression.^[10] If vision cannot be improved with contact lenses and the cornea becomes too thin or scarred, a corneal transplant may be necessary.^[4]

Keratoconus affects about 1 in 2,000 people, though some estimates suggest it may be as common as 1 in 400.^[4][9][11] It typically develops in late childhood or early adulthood and occurs in all populations, though it may be more common in some ethnic groups, such as people of Asian descent.^[9] The name comes from the Greek kéras (cornea) and Latin cōnus (cone).^[12]