Keratoconus means cone-shaped cornea
Keratoconus Definition - An eye disorder characterized by an irregular corneal surface (cone-shaped) resulting in blurred and distorted images. (American Academy of Ophthalmology, 2011)
The cornea is the window and outer surface of the eye. When you are visualizing an image, light travels through the cornea, then through the lens to the retina and then on to the brain to form a visual image. The normal corneal surface is smooth and dome shaped and aspheric (flattens towards the edges). Light rays passing through it move in an undistorted manner to the retina to project a clear image to the brain. This is the typical normal working cornea.
Keratoconus is a progressive eye condition that affects the cornea. The normally round, dome-shaped cornea weakens and thins, causing a cone-like bulge to develop. The regular curvature of the cornea becomes irregular, resulting in increasing nearsightedness (myopia) and astigmatism that have to be corrected with special glasses or contact lenses. Since the cornea is responsible for refracting most of the light coming into the eye, corneal abnormalities can result in significant visual impairment, making simple tasks difficult like driving or reading.
Symptoms of Keratoconus (EYE FACTS AAO worksheet, 2010)
- mild burning
- glare at night
- irritable eye
- sensitivity to light
- some distortion of vision
According to the American Academy of Ophthalmology, about 1/2000 people will develop keratoconus. Most people will have a mild or moderate form of the disease. Less than 10% of people with keratoconus will develop the most severe form. It typically is diagnosed in the late teens or twenties, however, many people have been diagnosed in their mid to late thirties. It is common for one eye to progress faster than the other and the eyes may go for long periods of time without any change and then change dramatically over a period of months. Rubbing the eyes is known to hasten progression, and modern treatments such as Intacs and collagen cross-linking may delay progression.