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| Keratoconus creates an irregular cornea that is a contraindication
for most refractive surgery, but can be treated with
Intacs inserts and/or CxL CrossLinking. |
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Keratoconus is a disease of
the cornea that makes the cornea become weak and gradually bulge
outward.
Causes
The exact cause of keratoconus is unknown. Many theories based on research and its association with other conditions attempt to identify a single cause, however, no one theory explains it all. Keratoconus tends to run in families, so a genetic link may be indicated. It is likely that keratoconus is caused by a combination of things including genetics, the environment, and the endocrine system.
Symptoms
Most often, the corneal bulging is in the lower half of the cornea
and first presents as astigmatism, however not all astigmatism is
due to keratoconus. The abnormal curvature of the cornea due to
keratoconus changes the cornea's refractive error producing moderate
to severe irregular astigmatism and blurriness of vision including monocular diplopia, or ghosting. As the
condition advances, scarring of the central cornea may occur.
Treatment
In
mild or early stages of keratoconus (forme fruste keratoconus),
eyeglasses may correct the astigmatic vision. Approximately half
of keratoconus patients have no negative lifestyle effects. The
cornea stabilizes after a few years without ever causing severe
vision problems.
As
keratoconus advances, rigid gas-permeable (RGP) contact lenses maybe
the only non-surgical way to achieve clear vision. Contact lens
fitting of a patient with keratoconus requires much care and frequent
check-ups, because the condition can worsen.
If keratoconus progresses the cornea may become unstable and the patient may require Penetrating Keratoplasty (PKP). Currently, between 10-30
percent of keratoconus patients require PKP because of contact lens intolerance, poor results from other
stabilization techniques, or because of scarring of the cornea that
causes loss of vision. PKP is highly successful
but requires a long healing period. After three years 90%-95% people
with advanced keratoconus have success with corneal transplant.
Alternative treatments for keratoconus
that may significantly reduce the probability of the need for PKP,
improve visual ability, stabilize the cornea, and halt or slow the
progression of keratoconus have recently become available.
Intacs,
which were originally used for refractive purposes, have caused
stabilization in keratoconus patients and may be a good choice to
reduce the possibility of keratoconus advancement. Keratoconus is
an indication for Intacs as a therapeutic treatment, which
adds material to the cornea. For keratoconus patients who are also myopic (nearsighted, shortsighted), Intacs can also correct
up to 3.00 diopters of myopia in a normal healthy eye, but can correct
significantly more refractive error in a eye affected by keratoconus.
Additionally, by making the cornea more regular, patients who had
become contact lens intolerant may be able to again wear contacts
after Intacs.
Used as a therapeutic
treatment for keratoconus and corneas that have become unstable
or weak due to ectasia, Corneal CrossLinking with Riboflavin (CxL) is a technique where the eye is flooded with a riboflavin solution
and exposed to ultra high frequency light. CxL apparently
causes the collagen fibrils to thicken, stiffen, and reattach to
each other, making the cornea stronger and more stable. CxL
is a new and noninvasive therapy that has been showing significant
improvement for some patients with keratoconus.
Contraindication for Refractive Surgery
Keratoconus is a strong contraindication
for conventional or custom wavefront Lasik, Bladeless Lasik, PRK, LASEK, Epi-Lasik, or any refractive surgery technique that removes tissue, due to the
high probability that these procedures may further weaken a cornea
affected by keratoconus.
RLE and P-IOL are lens-based procedures that neither add nor subtract
from the cornea, however advanced keratoconus may require other
surgery that would be best performed before RLE or P-IOL.
Looking For Best Lasik Surgeon?
If you are ready to choose a doctor to be evaluated for conventional
or custom wavefront Lasik, Bladeless Lasik, PRK, or any refractive surgery procedure, we recommend you consider a doctor who has been evaluated and certified by the USAEyes nonprofit organization.
Locate a USAEyes Evaluated & Certified Lasik Doctor.
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