[Excimer laser photorefactive keratectomy retreatment following photokeratectomy under-correction]

Results of excimer laser photorefractive keratectomy are well accepted for the correction of low to moderate myopia. However, the occurrence of a regression is still a frequent complication. The purpose of the present study is to evaluate the interest and risk of excimer photorefractive keratectomy retreatment of eyes that underwent a regression of the refractive effect.

A retreatment was achieved in 27 eyes of 22 patients. This reshaping was required because of either an expected undercorrected initial treatment, either a regression of the refractive effect of the first photorefractive keratectomy that did not respond to the topical steroid therapy. As we used two different types of excimer laser to achieve the retreatments, we formed two subgroups. In the first sub-group, 13 eyes were retreated with an Excimed (Summit), and in the second one, that included 14 eyes, a laser EC5000 (Nidek) was used. The delay between the first procedure and the retreatment was 16.38 +/- 7.56 months in the first sub-group and 29.85 +/- 13.09 months in second one. The mean attempted correction for the reshaping was -3.01 +/- 1.25 diopters in the first sub-group and -1.63 +/- 0.80 diopters in the second one.

No specifical problem was encountered during the retreatment. Specifically, we did not observe any decentring. By the third post-operative month, patients recovered a mean uncorrected visual acuity of nearly 7/10 in both sub-groups. This mean uncorrected visual acuity did not regressed during the follow-up. In addition, the mean post-operative refraction was 0.11 +/- 0.78 diopters in the first sub-group and -0.20 +/- 0.59 diopters in the second, three months after reshaping. The final refraction was -0.15 +/- 0.30 dioptres in the first sub-group and -0.70 +/- 0.62 dioptres in the second one. Nine eyes exerienced a regression during the follow-up period, from which three responded to the topical steroids. These regressions occurred in 4 eyes from the first sub-group and 5 of the second one. No other complication were observed.

Although there is a aggreement about the efficacy of excimer laser in the treatment of low or moderate myopia, regressions of the refractive effect is not unfrequent. It can warrant a reshapping. Our results demonstrate the simplicity and the predictive value of excimer laser in the retreatment of these regressions after photorefractive keratectomy. This method seems more accurate than radial keratotomy.

Excimer laser retreatment is highly effective in the correction of undercorrection after a previous procedure of photorefractive keratectomy, especially when the attempted correction of the initial treatment was under -6 diopters.