Keratoconus is a progressive disease, often appearing in the teens or early twenties, in which the cornea thins and changes shape. The cornea is normally a round or spherical shape, but with keratoconus the cornea bulges, distorts and assumes more of a cone shape. This affects the way light enters the eye and hits the light-sensitive retina, causing distorted vision. Keratoconus can occur in one or both eyes.
Keratoconus can be difficult to detect, because it comes on slowly. You may have distorted and blurred vision. You might also notice glare and light sensitivity. Keratoconic patients often have prescription changes each time they visit their optometrist. It’s not unusual to have a delayed diagnosis of keratoconus, if the practitioner is not familiar with the early-stage symptoms of the disease.
Causes of keratoconus are unclear. A genetic link may exist, as you may find several keratoconics within an extended family.
In the mildest form of keratoconus, spectacles or soft contact lenses may help. But as the disease progresses and the cornea thins and changes shape even more, spectacles or soft contacts will no longer correct your vision. Rigid gas permeable contact lenses are the next correction method of choice.
The firmer material of a rigid contact lens holds the cornea in place better than a soft contact lens. Fitting contact lenses on a keratoconic cornea is delicate and time-consuming. You can expect frequent return visits to fine-tune the fit and the prescription. The process will begin again when the cornea thins and distorts even more, altering the contact lens fit and prescription needed for clear, comfortable vision.
