Corneal cross linking is vital for patients with keratoconus, helping to stabilize their vision and prevent further deterioration of corneal health.
Corneal cross linking (CXL) is a procedure that uses a combination of ultraviolet A (UV-A) light, a photosensitizing agent called riboflavin (vitamin B2), and oxygen to create additional bonds between collagen fibers in the cornea. These new bonds increase the biomechanical strength of the cornea and stabilize its shape.
In essence, the process mimics the natural cross-linking that occurs slowly over a lifetime, but it accelerates the effect to provide timely reinforcement for the cornea. This is especially important for patients with conditions like keratoconus, where the cornea gradually thins and bulges outward, causing significant visual disturbances.
The principle behind corneal cross linking is to use a controlled photochemical reaction that induces the formation of covalent bonds between collagen molecules. This carefully orchestrated process typically lasts about one hour, with some variations depending on your specific condition and the protocol used by our cornea specialist. Here’s the procedure in a nutshell:
Prior to the procedure, patients may need to stop wearing contact lenses for a period of days or weeks. This helps ensure that the cornea’s surface is in an optimal state for treatment.
Anesthetic eye drops are administered to create comfort during the treatment. This ensures that patients experience little to no pain during the procedure.
In the standard FDA-approved epi-off method, the outer layer of the cornea (the epithelium) is gently removed. This removal allows riboflavin to penetrate deeper into the corneal tissue.
Riboflavin eyedrops are applied to the cornea for about 30 minutes. This vitamin B2 solution acts as a photosensitizer ready to absorb UV-A light.
Once the cornea is saturated with riboflavin, a focused beam of UV-A light is directed onto the eye for another 15 to 30 minutes. The combination of UV-A light, oxygen, and riboflavin triggers the chemical reaction that creates the new collagen bonds.
After the UV-A exposure, a soft bandage contact lens is placed on the eye. Patients then apply antibiotic and anti-inflammatory eye drops as their eye heals over the following days.
There are two main methods for delivering corneal cross linking: the epi-off method and the epi-on method. The epi-off technique involves the removal of the corneal epithelium prior to treatment, allowing for deeper penetration of riboflavin and a well-established success rate of around 95%. Although effective, the epi-off procedure typically involves a longer recovery time and can result in more discomfort during the healing phase.
The epi-on or trans-epithelial method, on the other hand, maintains the epithelium intact. This approach may result in a more rapid recovery and reduced discomfort; however, its long-term success rate is not as well established because the intact epithelium can act as a barrier to riboflavin penetration. Therefore, the FDA-approved standard remains the epi-off protocol for most patients.
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The primary benefit of corneal cross linking is its ability to stabilize the cornea and arrest the progression of conditions such as keratoconus. These benefits are a key reason our cornea specialist recommend the treatment when appropriate evidence of corneal progression is observed. Stabilizing the cornea can lead to several key improvements and benefits:
Successful cross linking can halt the worsening of corneal deformation. This reduces the long-term risk of severe vision loss and the potential need for more invasive interventions, such as a corneal transplant.
A strengthened cornea can lead to better contact lens fittings and overall visual stability, which may also enhance the quality of life for patients.
In the past, a significant percentage of severe keratoconus cases required corneal transplants. Cross linking helps diminish this risk by stabilizing the thickness and shape of the cornea.
While cross linking does not reverse pre-existing corneal damage or significantly correct refractive errors, many patients experience a slight improvement in their visual acuity after the procedure.
Before proceeding with cross linking, our cornea specialist perform a comprehensive evaluation to ensure that the benefits of treatment outweigh any potential risks. This evaluation includes a detailed assessment of corneal topography, pachymetry (corneal thickness measurements), and visual function tests.
The most common indication for the procedure is progressive keratoconus – a condition where the cornea steadily thins and becomes cone-shaped.
The procedure is generally recommended for patients whose corneas are thicker than 400 microns. For patients with slightly thinner corneas, modified protocols using hypo-osmolar riboflavin may be considered to safely thicken the cornea before treatment.
The best outcomes generally occur in patients who are in the age range of 14 to 65, although patients as young as 8 may still be a good candidate. Younger patients, particularly children and adolescents with rapid disease progression, may be treated promptly to prevent further deterioration.
Candidates should have a generally healthy ocular state with no significant infections or severe ocular surface diseases. A prior history of herpetic infection or ocular surface issues might prompt caution or an alternative management strategy.
Contact our office today to find a top optometrist near you who can provide personalized evaluations and treatment options.
Corneal cross linking is an essential treatment for keratoconus, focusing on strengthening and stabilizing the cornea for better eye health.
