Fellow eye study compares wavefront-guided LASIK and PRK

April 29, 2007

A randomized, prospective, contralateral eye study is under way comparing the efficacy, predictability, safety, and visual performance of wavefront-guided refractive surgery with all-laser thin-flap LASIK or PRK, said Edward E. Manche, MD, director of cornea and refractive surgery, Stanford University School of Medicine, Stanford, CA.

A randomized, prospective, contralateral eye study is under way comparing the efficacy, predictability, safety, and visual performance of wavefront-guided refractive surgery with all-laser thin-flap LASIK or PRK, said Edward E. Manche, MD, director of cornea and refractive surgery, Stanford University School of Medicine, Stanford, CA.

Dr. Manche, single surgeon in the study, reported outcomes to 1 month from 22 eyes of 11 enrolled subjects. Mean spherical equivalent in both groups is about –5.7 D. All ablations are being performed with an excimer laser (STAR S4, Advanced Medical Optics [AMO]/VISX). The 60 kHz femtosecond laser (IntraLase, AMO) is being used for LASIK flap creation (mean achieved flap thickness, 101.7 ± 16 μm) and standard mechanical epithelial removal is being performed in the PRK eyes.

"The early results are showing the expected benefit of LASIK for faster visual recovery, but so far both procedures have been associated with excellent predictability and safety," Dr. Manche said. While all LASIK eyes achieved 20/20 or better uncorrected visual acuity (UCVA) by 1 week and all had 20/16 or better UCVA at 1 month, more than 50% of PRK eyes had worse than 20/40 UCVA at 1 week and at 1 month, 100% were only seeing 20/40 or better.

Loss of best-spectacle corrected visual acuity (BSCVA) was greater in the PRK eyes at 1 month, but Dr. Manche noted the loss seems to disappear by 3 months. Both groups showed early reductions in 5% and 25% contrast BSCVA.

There were no intraoperative or postoperative complications, including no cases of corneal haze rated worse than trace in the PRK eyes despite an average correction approaching 6 D.

Analyses of wavefront aberrations showed no significant differences between groups, but a trend toward greater increases in total higher-order aberration root mean square, coma, and spherical aberration in the LASIK eyes.