Keratoconus

What is keratoconus?

Keratoconus is a disorder of the anterior surface of the eye (the cornea). It is a progressive eye disease in which the normally round cornea thins and begins to bulge into a cone-like shape. This bulging cone shape deflects light as it enters the eye on its way to the light-sensitive retina, causing distorted vision.

The distortion caused by keratoconus has been compared to viewing a street sign through your Keratoconus can occur in one or both eyes and often begins during a person’s teens or early 20s. The progression of keratoconus is unpredictable but generally the condition progresses slowly and can cease at any stage.  While keratoconus interferes with the clarity of a person’s sight it rarely causes blindness and in its early stages, keratoconus causes slight blurring and distortion of vision and increased sensitivity to glare and light. As the disorder progresses, the degree of vision obtained through glasses becomes less acceptable and contact lenses often become the best method of correcting vision problems. The actual incidence of keratoconus is estimated to occur in 1 to 5 persons per 1,000 in the general population.

What are the signs and symptoms?
Keratoconus can be difficult to detect, because it usually develops slowly. However, in some cases, keratoconus may proceed rapidly.

• As the cornea becomes more irregular in shape, it causes progressive nearsightedness and irregular astigmatism to develop, creating additional problems with distorted and blurred vision.
• Glare and light sensitivity may occur.
• Often, keratoconic patients experience changes in their eyeglass prescription every time they visit their eye care practitioner.
• Some may report flare or halos around lights, particularly when driving at night.
• Ghost images, seeing double with one eye covered (monocular diplopia), and multiple images are common complaints.

What causes keratoconus?
The characteristics of keratoconus have been known for at least 200 years, but the specific causes are still unknown. Several theories have been proposed:

• One scientific theory is that keratoconus is genetic in origin. About 7% of patients have other family members with the disease.
• Keratoconus is a degenerative condition perhaps linked to the imbalance between enzymes and inhibitors within the cornea. This imbalance makes the cornea more susceptible to oxidative damage from compounds called free radicals, causing it to weaken and bulge forward.
• Keratoconus may also be secondary to some disease processes.
• A hypothesis has also been proposed that keratoconus may involve the endocrine system (hormones) since the condition is often diagnosed in young people at puberty or in their late teens.
• Some researchers believe that allergy, excessive eye rubbing and a history of poorly fitted contact lens may play a role.

Any treatment for keratoconus?

Glasses
Patients with very mild disease may initially be corrected with glasses.

Soft contact lens/ Rigid gas permeable lens
Some may be corrected with soft contact lenses, however the vast majority of patients need rigid contact lenses. This is because the disease progresses and the cornea thins and becomes increasingly more irregular in shape, glasses and soft contacts no longer provide adequate vision correction.

Intacs
Intacs may be needed when keratoconus patients no longer can obtain functional vision with contact lenses or eyeglasses. It is a method for flattening the cornea that is too steep and making a patient more contact lens tolerant. This procedure is good for patients who are contact lens intolerant and who want to avoid a corneal transplant.

Cornea collagen cross-linking
This non-invasive procedure strengthens corneal tissue to halt bulging of the eye’s surface in keratoconus.

Corneal transplant
Corneal Transplants are the only option for patients who have scarring in the center of the cornea or who are contact lens intolerant because their corneas are too steep, which no longer giving them acceptable vision. The results of corneal transplants are excellent in keratoconus patients with an over 97% success rate.