Corneal Ectasia · A Comprehensive Evaluation · Advanced Treatment & Surgery
Corneal Cross-Linking
Corneal cross-linking is the only treatment demonstrated to halt the progression of keratoconus. By strengthening the collagen bonds within the corneal stroma using UV-A light and riboflavin, CXL arrests the disease process and preserves the corneal tissue needed for all future vision correction strategies. Two protocols are offered: epithelium-off (Dresden standard) and EpiOxa epithelium-on (FDA-approved 2023).
— How it Works
Mechanism of Cross-Linking
Keratoconus weakens the covalent bonds between collagen fibrils in the corneal stroma. CXL introduces new chemical cross-links between these fibres, increasing the biomechanical stiffness of the corneal stroma by approximately 300% in vitro — arresting the progressive ectasia.
The procedure relies on the photochemical reaction between riboflavin (vitamin B2) and UV-A light at 365 nm. Riboflavin acts as a photosensitiser, generating reactive oxygen species that form covalent bonds between adjacent collagen molecules in the anterior stroma.
CXL does not reverse existing corneal distortion — it stabilises the cornea at its current shape. For this reason, early treatment before significant corneal irregularity develops leads to the best long-term outcomes.
— Key Metrics
Wavelength
365nm UV-A
Photosensitizer
Riboflavin (Vitamin B2)
Standard Fluence
3 mW/cm2 × 30 min.
Protocol
EpiOxa Epithelium-On Cross-Linking
What is the difference between Epi-On vs Epi-Off Cross-Linking?
“Epi-On” Cross-Linking
or “Epithelium-On” cross-linking, is the preferred technique used in Europe. Also called trans-epithelial cross-linking, this variation of the cross-linking technique does not remove the epithelial cells on the corneal surface. Riboflavin and UV light is directly applied to the surface of the eye for the cross-linking procedure. This allows for a faster, less painful recovery after the procedure, without any difference in therapeutic efficacy.
“Epi-Off” Cross-Linking
or “Epithelium-Off” cross-linking is the variation of the technique approved by the FDA for use in the United States. This is mostly historical, as the original clinical trials done in the United States were performed using this older technique. Therapeutic efficacy of both techniques is the same. During “Epi-off” cross-linking, an alcohol solution is used to loosen up surface epithelial cells on the cornea. A special surgical brush is then use to remove the cells. Riboflavin and UV light are then applied to the surface of the eye for the cross-linking procedure. A bandage contact lens is then placed over the eye. Recovery is usually a little longer from this variant of the technique, as new epithelial cells need to regrow over the corneal surface.
Dr. Jimmy Hu offers both “Epi-On” and “Epi-Off” Cross-Linking for treatment of keratoconus and corneal ectasias. At your consultation, Dr. Hu will discuss with you which variant of the procedure is best suited towards your needs.
What should I expect from the Cross-Linking Procedure?
This procedure is usually done one eye at a time. A bandage contact lens is placed over the eye, and the eye may feel scratchy and sensitive to light for a few days.
The recovery time is about three to five days. With “Epi-On” cross-linking, pain and recovery as usually a little faster, and less painful. Visual recovery takes about four weeks. Some patients may experience a small improvement in uncorrected visual acuity and a decrease in astigmatism. This may result in a change of prescription for contact lenses/glasses.
When should I have cross-linking performed?
For most patients with keratoconus, as they continue to age, keratoconus is expected to worsen and deteriorate. Vision may also deteriorate. Cross-linking is generally recommended for patients with early, and mild-moderate keratoconus in order to halt progression, and preserve vision. The primary goal, is to prevent keratoconus from getting worse, so that it never gets severe enough to require a corneal transplant.
In general, cross-linking only needs to be performed once, and its effects last for a lifetime.
— Book a Cross-Linking Evaluations
One goal: halt progression
Dr. Hu evaluates serial topographic data to determine whether CXL is indicated and which protocol is most appropriate for your corneal thickness, lifestyle, and bilateral treatment needs.