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Keratoconus
Keratoconus is a degenerative condition that progressively thins an area of the cornea causing a
bulging or "cone" shape in the thinned area. The cornea is the front clear window of the eye
which focuses light onto the retina. The cornea is normally smooth and round like a dome in shape,
however in Keratoconus, the cornea becomes very thin, irregular, and starts to protrude like a cone.
This protruding cone shape affects the central cornea and causes the vision to become distorted.
Keratoconus is usually present in both eyes with one eye progressing faster than the other.
The cause of Keratoconus is currently unknown but some factors thought to be associated with the
disease are allergy and heredity. People with Keratoconus almost always seem to be "eye rubbers."
It is not known whether the Keratoconus causes the intense itching or if the itching is already present
causing the eye rubbing which leads to the condition. One thing is for certain, however, continued
eye rubbing causes the condition to worsen significantly. It is for this reason that people with
Keratoconus must not rub their eyes and are often prescribed medications to relieve the itching.
About one in two thousand people have the condition.
Eyeglasses may be used to treat the problem only in the early stages of the disease. Glasses will
not provide good vision as the disease progresses. If the condition is not too advanced, special
soft contact lenses can be used to provide vision. Rigid gas permeable contacts, however, will provide
superior vision correction and are certainly the preferred treatment in moderate to severe cases.
The contact lens acts as a new regular shaped clear front surface of the eye to focus light onto the retina.
As Keratoconus progresses, the tip of the cone continues to thin and sometimes scars. If the cornea
becomes too thin and pointed to the point that the contact lens cannot stay on the eye, a corneal
transplant (called keratoplasty) is necessary. This involves removing the thinned cornea and sewing
a donor cornea in its place. Most patients however, can be managed well with contact lenses and
only about 10% of Keratoconus patients require a keratoplasty. It is important to note that
even after a keratoplasty, special rigid gas permeable contacts are often needed to correct vision.
Contact lens fitting in Keratoconus is very different than cosmetic contact lens fitting. It can be
a very time intensive and challenging procedure for both doctor and patient. Special curves on the
back surface of the lens are needed to fit over the pointed area of the cone. This can require numerous
office visits and lens adjustments to accomplish. Keratoconus patients have more sensitive corneas
and some awareness or mild discomfort with contacts is common. First time lens wearers may require an
adaptation period before comfort is attained.
Once you are fit with contacts, you will need to be monitored every six months for changes in the cone.
Adjustments in your contacts will be needed as the cone continues to protrude. Failure to adhere to
follow up visits can cause corneal damage. If the cone protrudes further and the contact lens is now
relatively flat with respect to the new corneal shape, mechanical stresses are placed on the cornea
resulting in central scarring. The scar tissue that forms in the center of the cornea can impair the
vision significantly. I advise all Keratoconus patients to obtain prescription glasses for emergency
back up even though vision is typically not good with glasses. Purchasing a spare set of contacts is
also wise since the Keratoconus patient is so heavily dependant on their contacts for normal daily
function. Should a contact get lost or broken, the Keratoconus patients may find themselves unable to
do simple daily activities until a new lens is obtained. Since these contacts are very special,
they sometimes can take a significant amount of time to replace.
The condition may progress to the point that contact lenses cannot provide good usable vision or that the
vision is still well corrected but it has become impossible to keep a contact lens on the eye. If this
point is reached a keratoplasty is indicated. After the corneal transplant is performed and the healing
process is over, the individual will again be placed into special contact lenses to provide good quality vision.
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