Myopic PRK safe, stable in long-term follow-up

Photorefractive keratectomy for myopia remained safe and its refractive results stable over the course of 8 years of follow-up, according to a group of Finnish researchers.

Juhani Pietilä, MD, and colleagues at the University of Tampere evaluated the 8-year results of PRK in 92 myopic eyes of 55 patients. The treated eyes were divided into three groups according to preoperative refraction: low myopes (less than –6 D), medium myopes (from –6.1 D to –10 D) and high myopes (greater than –10 D).

Regression stabilized in all groups within 12 months, although small shifts occurred up to 8 years postoperatively. Mean change in refraction from 2 to 8 years was less than –0.5 D, regardless of preoperative refraction, the authors said.

The mean myopic shift for low myopes was –0.42 D, for medium myopes –0.37 D and for high myopes –0.41 D. The percentage of eyes within 1 D of emmetropia 8 years after the initial PRK procedure was 78% in the low myopes, 69% in the medium myopes and 57% in the high myopes group.

Only one eye lost 2 lines of best corrected visual acuity, and this was attributed to irregular astigmatism. Residual corneal haze was observed in 13% of eyes, but the haze had no effect on VA, the study authors said.

“We found that change in refraction correlated significantly to preoperative refraction during the first postoperative year, but not with change in refraction between 2 and 8 years,” the authors wrote in the March/April issue of Journal of Refractive Surgery.