|Keratoconus and Cornea Collagen Cross-Linking (CXL / C3-R ) at ISEC
The CORNEA is the transparent lens in the front part of the eye. Together with the crystalline lens inside the eye, the cornea bends and focuses incoming light, accounting for approximately two-thirds of the eye’s total optical power. The incoming light rays are focused onto the retina to project a clear visual image to the brain.
The normal cornea surface is smooth and round in the center, flattening towards the outer edges.
KERATOCONUS, from the Greek words meaning cone-shaped cornea, is a degenerative disorder of the eye in which structural changes within the cornea causes it to thin and change from a normal spherical rounded shape, to a more irregular conical shape, resulting in a distortion of the images being projected onto the retina.
Keratoconus can cause substantial distortion of vision, usually with a rapid increase in myopia (short-sightedness) and/or astigmatism. Patients often complain of “substandard” quality of vision, even with spectacle wear, resulting in frequent changes in glasses prescriptions. It is typically first diagnosed in young adolescent patients, but may also present in much younger or older age groups.
Generally in keratoconus, it is the lower half of the cornea that becomes distorted and usually first presents itself as irregular astigmatism. Glasses or contact lenses can initially correct for this distortion but in advanced stages of keratoconus, glasses and contact lenses can no longer compensate for the severe distortions. Although keratoconus causes irregular astigmatism, most forms of astigmatism are not related to keratoconus and are simply the effects of a slightly oval shaped cornea. This can be confirmed with an accurate refraction by an experienced optometrist or eye specialist.
In the early stages of keratoconus (sometimes called forme fruste keratoconus or FFKC), optometrists can often assist a patient by prescribing glasses or contact lenses. Some special contact lenses (especially the rigid gas permeable (RGP) types ) have been designed to specifically help those who suffer from keratoconus. Newer silicone hydrogel soft contact lenses have also recently become available specifically for early cases of keratoconus. These have the advantage of being much more easily tolerated and a little more comfortable to wear. (These are now available at ISEC.)
Keratoconus often becomes progressively more severe in the twenties and thirties. If both eyes are affected, the deterioration in vision can affect the patient’s ability to drive a car or read normal print. However, it often affects one eye more than the other eye.
In most cases, corrective lenses (spectacles, special soft or rigid gas permeable ( RGP ) contact lenses ) are often effective enough to allow the patient to continue to drive legally and likewise function normally for a while.
Advanced stages of keratoconus will usually require surgical intervention to obtain good vision. These include insertion of temporary intrastromal corneal ring segments (eg. Intacs) to improve the shape of the cornea and allow an improvement in vision, and other surgeries like cornea transplants. Traditionally, approximately 10-20% of patients may eventually require corneal transplantation (penetrating keratoplasty (PKP) or lamellar keratoplasty (eg.DALK) ).
However, despite the disease’s unpredictable course, keratoconus can often be successfully managed with little or no impairment to the patient’s quality of life.
In the last few years, an innovative treatment known as CORNEA COLLAGEN CROSS LINKING (CXL or C3R) with riboflavin has been shown to help limit and slow the progression of keratoconus in a large number of patients worldwide, with few reported side effects. This treatment has been available at ISEC since 2008.