Excimer laser photorefractive keratectomy for hyperopia

Excimer laser photorefractive keratectomy has generated considerable interest as a technique for correcting myopia. In this study, the excimer laser was used to correct hyperopia.

A prospective clinical study based on the results of photorefractive keratectomy in 23 consecutive hyperopic eyes (one eye per patient) is presented. The excimer laser used in this study was a MEL 60 (Aesculap-Meditec); this laser emits 193-nanometer laser light. A 1-year follow-up study of two groups of eyes was performed. All patients were followed for 12 months. The first group comprised 15 hyperopic eyes with preoperative refraction between +2.0 and +7.5 diopters (mean spherical equivalent +4.7 +/- 1.6 D). The second group comprised eight aphakic eyes with preoperative refraction between +11.0 and +16.0 D (mean spherical equivalent +13.1 +/- 2.0 D).

In group 1, 12 eyes (80%) were within +/- 1.0 D of the intended correction (baseline, +2.0 to +7.5 D) after 1 year. In group II, only three of the eight aphakic eyes (37%) were within +/- 1.0 D of the intended final refraction (baseline, +11.0 to +16.0 D). The stability of refraction in group I was better than in group II. At 12 months, best corrected visual acuity was unchanged in 14 eyes of group I. One eye had lost two lines. In group II, best corrected visual acuity was unchanged in six eyes after 12 months. In two eyes, best spectacle-corrected visual acuity was lower than the preoperative value, because of decentration of the ablation zone. After 1 year, 80% of the eyes in group I and 25% of those in group II had a visual acuity of 20/40 or better.

Photorefractive keratectomy is an efficient and relatively safe procedure for correcting hyperopia up to +7.5 D. The predictability is good. Results of photorefractive keratectomy to correct highly hyperopic (aphakic) eyes are not as encouraging. Three patients in this study lost one to three lines of best spectacle-corrected visual acuity due to decentration of the clear zone. Two of the patients belonged to group II. Therefore, we do not recommend photorefractive keratectomy in highly hyperopic eyes, especially if they are aphakic, because even slight decentration may lead to loss of best corrected visual acuity. As in other refractive surgical procedures, great care must be taken to improve the centration of the clear zone.