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Keywords:

  • Cross-cylinder;
  • photorefractive keratectomy;
  • astigmatism

Abstract

Background

To compare efficacy and safety of photorefractive keratectomy (PRK) by cross-cylinder with single methods in medium-high astigmatism.

Design

Randomized clinical trial study

Participants

Fifty patients with medium-high compound myopic astigmatism were enrolled between September 2007 and September 2008.

Methods

PRK was performed on 100 eyes of 50 patients with compound myopic astigmatism. Each patient underwent PRK by cross-cylinder approach in one eye and single method on the contralateral eye. Vector analysis was used to assess astigmatic results.

Main Outcome Measures

Improvement of visual acuity (snelen chart), refraction, aberrometry.

Results

Uncorrected visual acuity (UCCA) equal to 20/40 or better after six months, was achieved in 98% of eyes in the cross-cylinder method versus 96% in single method.. Mean preoperative spherical equivalent(SE) was -5.2 ±2.1 D in the cross-cylinder method versus -5.1 ±0.5 D in the single method. At six months, the mean SE was – 0.5±0.4 D and -0.6±0.3 D, respectively. Mean IOS was 0.4±0.3 in the cross-cylinder group and 0.4±0.4 in the single group. Mean postoperative absolute change in total root-mean-square higher order aberrations in the cross-cylinder group and single group were 0.16 pm and 0.17 pm, respectively. Any of the mentioned differences didn't appear to be statistically significant.

Conclusions

Both PRK methods appeared to be safe and effective in correcting medium-high astigmatism.