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Scanning laser polarimetry in corneal topographic changes after photorefractive keratectomy
1School of Medicine, Gazi University, Ophthalmology Department, Ankara, Turkey.
Purpose:
To examine whether, or not, corneal topographic changes after excimer laser photorefractive keratectomy (PRK) for myopia and myopic astigmatism have any influence on measurements of the retinal nerve fiber layer (NFL) with scanning laser polarimetry.
Methods:
Retinal NFL thicknesses were determined by scanning laser polarimetry in 17 eyes of 13 patients with myopia and myopic astigmatism before and after PRK. Total ablation depth ranged from 26 to 71 microm. We used the relative ratios for superior and inferior NFL thicknesses which were calculated by dividing the NFL values of respective regions by the nasal value.
Results:
The mean superior NFL ratio measured was 3.02 +/- 0.92 preoperatively, and 3.00 +/- 0.76 postoperatively. The mean inferior NFL ratio was 2.95 +/- 0.75 preoperatively, and 2.99 +/- 0.66 postoperatively. There was no statistically significant difference between preoperative and postoperative NFL measurements (Wilcoxon signed rank test, p > 0.05).
Conclusions:
Corneal topographic changes after PRK have no significant influence on NFL measurements by scanning laser polarimetry. Our results suggest that scanning laser polarimetry can be used as a reliable method for retinal NFL thickness measurements even after excimer laser PRK.