I. Kremer et al., ONE-YEAR FOLLOW-UP RESULTS OF PHOTOREFRACTIVE KERATECTOMY FOR LOW, MODERATE, AND HIGH PRIMARY ASTIGMATISM, Ophthalmology, 103(5), 1996, pp. 741-748
Objective: To study the efficacy of excimer laser photorefractive kera
tectomy (PRK) for high, moderate, and low degrees of primary myopic as
tigmatism. Patients and Methods: Ninety-two eyes of 54 patients with d
ifferent degrees of compound myopic astigmatism underwent PRK. The eye
s were divided by degree of refractive astigmatism into three groups-h
igh (-2.75 to -5.0 diopters [D]), moderate(-1.25 to -2.50 D), and low
(less than or equal to-1.0 D). Refraction, corneal topography, slit-la
mp findings, and visual acuity with and without correction were assess
ed. Results: At 12 months, the mean reduction from the preoperative re
fractive cylinder was 80.7% in the high astigmatism group, 68.4% in th
e moderate astigmatism group, and 47.6% in the low astigmatism group.
The post-treatment residual cylinder axis remained stable in 23 (38.3%
) of 60 eyes and deviated in 37 (61.7%) of 60 eyes. The maximal deviat
ion of the residual cylinder axis was 15 degrees. Of the 89.2% of eyes
with low cylinder, 81.8% had moderate cylinder, and 85% of the eyes w
ith high cylinder achieved a final uncorrected visual acuity between 2
0/20 and 20/35 at 12 months. Conclusions: A statistically significant
reduction in the refractive cylinder was found in the high, moderate,
and low astigmatism groups. The difference between the mean reduction
of the high and moderate cylinders compared with the mean reduction of
the low cylinders also was found to be statistically significant. The
laser used in this study is an efficient tool for correcting high and
moderate astigmatism. However, regarding low astigmatism, it was foun
d to be less effective.