WHAT IS KERATOCONUS?
Keratoconus is a relatively common genetic degenerative disorder of the eye in which the cornea gets progressively thinner, changing the shape of the cornea and causing poor vision. The condition can be very mild in some but sight threatening in others.
WHAT CAUSES KERATOCONUS?
We do not fully understand the nature of this condition but we do know that in those people affected by keratoconus the collagen fibers in the cornea are genetically weaker. There is a familial tendency towards keratoconus but it is not necessarily passed from one generation to the next.
Blurring of vision, progressively increasing spectacle strength, poor night vision, sensitivity to bright light, streaking and distortion around light sources, ghost images. These visual symptoms are often accompanied by itchy, red eyes.
WHAT WILL HAPPEN TO MY EYES AND EYESIGHT?
Keratoconus is typically progressive. The cornea gets thinner and thinner causing myopia (short-sightedness) and astigmatism (irregularity and warping of the cornea). Initially glasses may be used to improve sight but eventually glasses are not effective and hard contact lenses become necessary to correct high levels of myopia and astigmatism. With time and with progressive corneal thinning contact lenses may no longer fit. The cornea may get so thin that it begins to scar and lose clarity.
If left untreated, about 25% of people with keratoconus will eventually have profoundly poor vision that cannot be corrected with glasses or contact lenses.
WHAT TREATMENTS ARE AVAILABLE?
Keratoconus is quite often an incidental finding and might already be non-progressive by the time it is diagnosed.
• Eye drops:
Rubbing of the eyes must be avoided as we believe this accelerates thinning of the cornea. Many patients with keratoconus also have allergic conjunctivitis and itchy eyes. Anti-allergy drops are very important to remove itching and the stimulus for rubbing. Patanol and Relestat are examples of excellent drops for allergy and are available over the counter.
• Spectacles and hard contact lenses:
These are important to allow good vision but do not alter the course of the disease process. In keratoconus, laser refractive surgery to eliminate the needs for glasses and contacts is totally contraindicated and will dramatically worsen the condition of the eyes.
• Collagen crosslinking:
For early and intermediate keratoconus a procedure known as collagen cross-linking can halt the progression of the corneal thinning. This procedure is very useful in avoiding the need for transplantation but it needs to be done in the early to moderate stages of the disease process. Crosslinking is not effective in the late stages of keratoconus where the cornea is already too thin or is already scarred. In patients older than 25-30, cross linking is rarely needed because the disease process has effectively come to an end by then.
• Corneal transplantation:
For advanced keratoconus with scarring or an extremely thin cornea a corneal transplant is necessary. The abnormal thin or scarred tissue is surgically removed and normal corneal tissue donated by a deceased individual is sutured into its place.
THE WAY FORWARD
A scan of the cornea with a machine called the Pentacam is necessary to get an objective and highly accurate assessment to make a definitive diagnosis. In patients younger than 30, scans should be repeated periodically so that deterioration and progressive thinning can be identified and treated accordingly.
If the cornea is deemed suitable and the disease process appears to be progressive, the crosslinking procedure is advisable to prevent further deterioration. This procedure is done as an outpatient in the consulting rooms.
If the disease process is deemed to be non-progressive, which is generally the case in those older than 30 years, no treatment is needed apart from allergy drops, glasses and/or contact lenses and visits to the optometrist 2 yearly.