The medical term for a condition in which the cornea becomes cone-shaped is keratoconus. The cornea is the transparent, curved front surface of the eye, and in keratoconus it gradually thins and bulges outward.
This altered shape prevents light from focusing normally on the retina. It can cause blurred or distorted vision, increasing nearsightedness, irregular astigmatism, double vision, and sensitivity to light. Both eyes are usually affected, although one may be more advanced than the other.
Keratoconus often begins in late childhood or early adulthood. Its exact cause is not fully understood, but genetic susceptibility, allergies, and frequent vigorous eye rubbing can contribute. Corneal topography maps the surface and is particularly useful for detecting early disease.
A common mix-up is with cataracts or glaucoma: cataracts cloud the eye’s lens, while glaucoma primarily damages the optic nerve. Early keratoconus may be managed with glasses or contact lenses; corneal collagen cross-linking can help slow progression.