Corneal nerves recovered more quickly after PRK than LASIK

PARIS — Corneal innervation recovers more quickly after PRK than LASIK, according to a confocal microscopy study presented here. Jay C. Erie, MD, and William N. Bourne, MD, found that neural recovery after LASIK was prolonged compared to PRK, and the number of sub-basal nerves was still reduced by 40% at 3 years after LASIK.

The study authors used custom software with a tandem scanning microscope to measure the nerve density in sub-basal nerve fibers. Their study was presented in a poster here at the European Society of Cataract and Refractive Surgeons meeting.

In their study, PRK was performed in 24 eyes of 14 patients using the Visx Star S2 excimer laser. Mean patient age was 40 years with a range of 22 to 53 years. The mean refractive error was –3.7 D with a range of –1.25 D to –5.75 D.

LASIK was performed on 17 eyes of 11 patients using the same laser. A planned 180 µm flap with a superior hinge was created using a Hansatome microkeratome (Bausch & Lomb). Mean patient age was 32 years with a range of 21 to 49 years. Mean refractive error was –6.6 D with a range of –2 D to –11 D.

The authors found that the mean number of sub-basal nerves was reduced by more than 90% at 1 month after both LASIK and PRK and was still less than 50% of preoperative levels at 1 year after both procedures. By 2 and 3 years after PRK, the number of sub-basal nerves was not significantly different from before PRK. In contrast, the number of sub-basal nerves 3 years after LASIK was still significantly lower than before LASIK.

The authors also measured corneal sensation using Cochet-Bonnet esthesiometry at 1, 2 and 3 years. According to the poster, “Normal corneal sensation, as tested by Cochet-Bonnet esthesiometry, is present at 1 through 3 years after PRK and LASIK.”