Keratoconus
Keratoconus is an irregular protrusion of the cornea, the clear surface
over the colored part of the eye. The cornea acts like the windowpane
to the eye. If this windowpane is not smooth, the light will not bend
evenly and an irregular image will be formed. Like looking through a bumpy
piece of glass.
During the early stages of this disease, vision may still be correctable
to 20/20 with glasses. The only clue to a keratoconus diagnosis may be
from corneal measurements or corneal map. A topographical map of the cornea
will show the high and low spots on the cornea, much like a topographical
map of the earth will show the mountains and oceans.
As this disease progresses, vision will no longer be correctable with
glasses. Iron will deposit around the base of the protrusion. The tissue
will thin and a scar may develop. In severe cases, a temporary painful
condition called acute hydrops may occur when water rushes into the thinned
area of the cornea. This will lead to severe scarring.
About one in 2000 people will develop keratoconus. Most people will have
a mild or moderate form of the disease. Only 10% of keratoconics 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; this is usually a more mild form of the disease. One eye
will precede the other and they will progress at uneven rates. The eyes
may go for long periods of time without any change and then may change
dramatically over a period of months.
A contact lens is the most highly effective way to manage keratoconus
and 90% of all cases can be managed this way indefinitely. If the cornea
becomes too scarred or painful, a corneal transplant may be necessary.
Contact Fitting over the keratoconus bump on the cornea
A gas permeable lens covers the irregular protrusion on the cornea and
makes a new smooth surface for the light to bend through. In many cases
a special design must be used. The back surface of the lens is designed
to fit the contour of the protrusion, much like fitting a hat to a head.
It is important for a patient with keratoconus to follow-up with his/her
eye doctor at a minimum of 6 month intervals to make sure there has been
no change to the cornea or contact lens.
The image above shows the topography of a keratoconus eye -- red is
high, blue is low.
This image shows the same eye with a contact lens on it. Note how
the lens has smoothed out the corneal surface.
These contact lenses are not cosmetic. They are a prosthetic device and
should be covered as any medical/prosthetic device is covered under the
patients’ insurance policy. Use of contact lenses may postpone or
eliminate the need for future, more costly and dangerous, surgical intervention
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