Keratoconus can predispose you to progressive vision loss, and this cornea disorder can also cause sensitivity to light. Although between 10-14 percent of keratoconus-afflicted people have a hereditary link, the cause is unknown in most people diagnosed with keratoconus. According to the American Academy of Ophthalmology, severe and progressive corneal thinning and/or severe vision loss is sometimes treated with cornea surgery.
The following describes the two options associated with corneal cross-linking (with a focus on cross-linking involving removal of the corneal epithelium), and what to expect if your ophthalmologist recommends that you undergo this typically outpatient corneal surgery.
“Epithelium-On” and “Epithelium-Off” Corneal Cross-Linking – Which Do You Need?
Corneal transplantation is not the only surgical treatment option for keratoconus. FDA-approved in 2016, corneal cross-linking is another surgical procedure to treat keratoconus. There are two primary options during corneal cross-linking, and these are referred to as “epithelium-on” and “epithelium-off” – with “epithelium-off” the more common corneal cross-linking surgical procedure.
As the cone-shaped cornea featured in keratoconus becomes progressively more abnormal over time, corneal fibers can weaken predisposing to corneal infection, ulceration, and eye pain (as well as blurred vision). Using a combination of ultraviolet A (UVA) light and riboflavin, corneal cross-linking surgery is performed to strengthen the corneal fibers and, thereby, stiffen the cornea and halt keratoconus progression. Removal of the epithelium is usually performed utilizing the Dresden Protocol (using a scalpel or rotating brush).
People with keratoconus who have autoimmune disorders (such as Lupus Erythematosus [SLE]) may not be considered candidates for the “epithelium-off” option. Since the rate of keratoconus is 50 percent higher in African-Americans as compared to caucasians (and SLE prevalence is far higher in African-Americans), the “epithelium-on” procedure may be more commonly-experienced in African-American people with keratoconus who have cross-linking surgery. However, the “epithelium-on” cross-linking procedure historically has not been as effective in improving vision in keratoconus-afflicted people.
Advantages of “Epithelium-Off” Corneal Cross-Linking
The following are three of the recognized advantages of removing the corneal epithelium during corneal cross-linking surgery:
- Better UVA and riboflavin absorption;
- More corneal flattening and corneal fiber strengthening (enabling corneal stiffening);
- Lower risk of post-surgery cornea ectasia progression (as compared to the “epithelium-on” procedure);
- More effective therapy to treat the progressive corneal elongation (ectasia) featured in keratoconus
On the other hand, the “epithelium-off” procedure in keratoconus-afflicted people who are not legally-blind (and tolerated Rigid Gas Permeable [RGP] contact lenses prior to surgery) is associated with a faster return to wearing RGP contact lenses.
Other Disorders Besides Keratoconus Treated by Corneal Cross-Linking
Three other eye disorders besides keratoconus that may necessitate the need for corneal cross-linking surgery are:
- Pellucid Marginal Degeneration;
- Terrien Marginal Degeneration;
- Post-refractive (e.g., LASIK) surgery ectasia
What to Expect During Corneal Cross-Linking
Corneal cross-linking usually takes place in an ambulatory surgery setting, and the patient remains awake (although relaxation medication and numbing anesthetic drops are generally provided). After the cornea’s epithelium is removed, insertion of riboflavin eye drops into the eye is performed, along with a 30-minute (or thereabouts) exposure to UVA light. The corneal cross-linking procedures typically takes only 60-90 minutes. After the surgical procedure is completed, light sensitivity and a feeling of a foreign body in the eye is commonly-experienced – but typically diminishes within several hours.
You can learn more about corneal cross-linking and other treatment options for keratoconus by speaking with a professional at one of the numerous offices across the US of the Precision Keratoconus Center.