Keratoconus or "coning" of the cornea
Keratoconus is an eye condition 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. As light enters the cone shaped cornea it is bent and distorted. Therefore, the light is unable to come to a point of clear focus on the light-sensitive retina.
Keratoconus usually affects both eyes, but the two eyes often progress at different rates. This disease typically begins during teenage years. In most patients, it progresses for several years before stabilizing in the third to fourth decade of life. In severe cases it can continue to worsen. In these cases the cornea continues to thin and bulge outward. This can result in further blurring of vision. Scarring of the cornea can also develop.
Symptoms of keratoconus:
- bulging, cone-shaped cornea
- glare and light sensitivity
- the need for frequent prescription changes
Who is at risk:
Researchers believe that approximately 3 million people worldwide have keratoconus. It affects males and females of all races throughout the world. The causes are still being researched, but the likelihood of developing keratoconus is greater if you:
- have a relative with keratoconus
- have had excessive laser eye surgery
- have hay fever, eczema, asthma or food allergies
In mild cases, glasses and soft contacts can be effective, but in more advanced cases, these no longer work well and custom contact lenses or surgery must be considered.
Gas permeable (GP) contact lenses
This is the primary treatment for keratoconus. To counteract the distortion of the cornea, most keratoconus patients require special hard lenses that help mold the corneal surface so that light can be focused clearly. Because the pattern of distortion in keratoconus is as unique as a fingerprint, the GP lenses are custom prescribed and manufactured.
Gas permeable contact lenses are the primary treatment for keratoconus.
A proper contact lens fitting is crucial to ensure optimal vision, comfort, and eye health. Poor fitting lenses can lead to corneal abrasions, scarring, and infection.
Many keratoconus patients will never require surgery, but it is an option in severe and advanced cases. Treatment is the performance of corneal transplantation. In this procedure, the scarred tissue is replaced with a section of donated cornea that is clear. About 10 to 20% of keratoconus patients will eventually require a corneal transplantation. However, corneal transplantation is not a cure in and of itself. Following a successful corneal transplant, most patients still need glasses, soft contacts, or GP lenses for adequate vision.
Patients with keratoconus must not have LASIK or PRK laser eye surgery due to an unacceptable risk of a poor outcome. The cornea in keratoconus is unusually thin and weak. For patients with keratoconus, LASIK surgery thins and weakens their corneas further. This can irreversibly destabilize the cornea and accelerate its distortion. Rubbing the eyes may also increase the progression of keratoconus.