FAQ and details
of the corneal collagen crosslinking trial at the
Royal Victorian Eye and Ear Hospital
What
is keratoconus?
Keratoconus is a thinning of the central zone
of the cornea, the front surface of the eye. As a result
of this thinning, the normally round shape of the cornea
is distorted and a cone-like bulge develops, resulting in
significant visual impairment.
What
causes keratoconus?
The cause of keratoconus remains unknown, although
recent research seems to indicate that it may be genetic in
origin. Certainly, some cases of keratoconus have a
hereditary component and studies indicate that about 8% of
patients have affected relatives. If there is no evidence
of keratoconus in successive generations of a family, there
is less than a 1 in 10 chance of the children of a person
with keratoconus also having the condition. Excessive
eye rubbing has also been implicated as a causative factor.
How common
is keratoconus?
Keratoconus is estimated to occur in 1 out of every
2000 persons in the general population. There appears
to be no significant preponderance with regards to either
men or women.
What
are the signs and symptoms of keratoconus?
The initial symptoms of keratoconus are usually
a blurring and distortion of vision that may be corrected
with spectacles in the early stages of the condition.
Frequent changes to the spectacle correction may be required
as the cornea becomes progressively thinner.
What
is the usual age of onset of keratoconus?
The onset of keratoconus can be anywhere between
the ages of 8 and 45. In the majority of cases, it becomes
apparent between the ages of 16 and 30 years.
Does
keratoconus affect both eyes?
Yes, keratoconus generally affects both eyes.
Only in a very small percentage of cases (<1%) is there
just the involvement of one eye. Even though keratoconus
is basically a bilateral condition, the degree of progression
for the two eyes is often unequal; indeed, it is not unusual
for the keratoconus to be significantly more advanced in one
eye.
Is keratoconus
associated with any other diseases or disorders?
Keratoconus has been associated with conditions
such as hay fever, asthma, eczema, double jointedness, Down's
syndrome, Marfan's syndrome and mitral valve prolapse.
Does
keratoconus cause blindness?
Keratoconus does not cause total blindness. However
it can lead to significant vision impairment resulting in
legal blindness.
How is
keratoconus treated?
In the early stages of the condition, spectacles
are usually successful in correcting the myopia and astigmatism
associated with the keratoconus. As the condition advances,
the cornea becomes highly irregular and vision is no longer
adequately corrected with spectacles. Rigid contact
lenses are then required to provide optimal visual acuity.
Soft contact lenses are usually not an option, as they cannot
correct for the irregular astigmatism associated with the
keratoconus. In about 15% of cases, the keratoconus
progresses to the stage where corneal transplantation is required.
