Keratoconus is a degenerative eye disease that causes the cornea to become progressively thinner. A normal cornea is round or spherical in shape, but with keratoconus, the cornea bulges forward, assuming more of a cone shape. This causes progressive steepening of the cornea shape and creates abnormal shape or "irregular astigmatism" of the cornea. As light enters the cone shaped cornea, it is bent and distorted and unable to come to a point of clear focus on the retina.

Normal eye

Keratoconus eye with a cone shape cornea

Keratoconus usually affects both eyes, but the two eyes often progress at different rates. This disease typically begins during teenage years and in the early stages, the diagnosis may be difficult to make. Most patients at this early stage can achieve good vision with glasses or contact lenses. In most patients, the disease progresses slowly for several years before stabilizing in the third to fourth decade of life. In some patients with more advance disease, there can be a sudden swelling of the cornea with pain and subsequent vision loss from corneal scarring.

It is believed that more than 3 million people world wide is afflicted with this eye disease. Many more are affected, but are unaware of the disease because they have such mild symptoms. The causes are still unclear, but there are some risk factors. These include family history, excessive laser eye surgery, hay fever, eczema and asthma. The signs and symptoms of keratoconus include: a bulging or a cone shape cornea, progressive nearsightedness and astigmatism, monocular double vision, glare and light sensitivity and the need for frequent prescription changes.

In mild cases, glasses and soft contact lenses can be effective, but in more advance cases, rigid gas permeable contact lenses are used. The rigid contact lens counteract the distortion of the cornea by providing a smooth surface that can focus light clearly on the retina. Because the pattern of distortion in keratoconus is unique for each case, the contact lenses are custom prescribed and manufactured. A proper contact lens fitting is crucial to ensure optimal vision, comfort, and eye health. Poor fitting contact lenses can lead to corneal abrasion, scarring and infection.

In advance cases of keratoconus, surgical intervention is necessary. If your eye doctor determines that you have significant scarring of the cornea or loss of vision from uncorrectable cornea distortion, a corneal transplant surgery may be recommended. In this procedure, a donor normal clear cornea replaces your diseased cornea. About 10 to 20% of keratoconus patients will eventually require a cornea transplant. Following a successful surgery, most patients still need glasses or contact lenses for adequate vision. There are other new procedures which may help stabilize the disease, but these and other unusual treatments should be discuss with your eye doctor to enable you to attain the best possible vision.