Early Clinical Experience With Corneal CXL at Byers Eye Institute at Stanford
Purpose
To treat and evaluate the first eight eyes enrolled in the UV-riboflavin crosslinking trial at Stanford for cornea ectasia from keratoconus or after LASIK surgery.
Methods
Pre-operatively, the patients’ ETDRS visual acuity, pupils, intraocular pressure, corneal thickness, pachymetry, and keratometry were taken along with a complete slit lamp examination.. The central 9 mm of corneal epithelium was removed with a spatula. Five drops of VibeX riboflavin were instilled into the eye every two min for twenty min. Pachymetry was then performed followed by five more drops of riboflavin onto the cornea Patients were randomized to one of three UV light intensity treatment arms:15 mW for 8 min, 30 mW for 4 min, and 45 mW for 2 min for 40 sec. A bandage contact lens was placed postoperatively. Best corrected and uncorrected visual acuity, pachymetry, IOP, and keratometry were measured at each follow up visit. All patients were put on Vigamox and a Flarex taper postoperatively.
Results
To date, 8 eyes have been followed to POM6 and 3 eyes to POM12. Two eyes were treated for post-LASIK ectasia while 6 eyes were treated for keratoconus. Mean logMAR BCVA pre-operatively was 0.68 (n=8), 0.30 at POM6 (n=8) and 0.40 at POM12 (n=3). Mean logMAR uncorrected VA remained unchanged from pre-op to POM6 and POM12. Mean pre-operative pachymetry measurements were 478 microns in the affected eyes, 437 at POM6, and 459 at POM12.. Mean keratometry measurements pre-operatively was 48.4 x 53.6 @ 92 at POM6 was 47.9 x 53.75 @ 108, and at POM12 was 47.2 x 54.0 x 117. All epithelial defects healed by POW1. Five eyes developed trace to mild central stromal haze persisted through POM6. None of the patients developed infections.
Conclusion
Epithelium-off corneal crosslinking out to twelve months post-operatively appears to be safe and leads to a decrease in corneal thickness and an improvement in best corrected visual acuity but no change in uncorrected visual acuity and keratometry measurements. Further follow up is necessary to determine the consistency and persistence of these findings.