Cooling effect on excimer laser photorefractive keratectomy
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Published on: September 20, 2024
Y Kitazawa1, E Maekawa, S Sasaki
1Department of Visual Science, Tokyo Medical and Dental University Graduate School, Japan.
Purpose:
To evaluate the effect of cooling on pain, corneal haze, and refractive outcome after excimer laser photorefractive keratectomy (PRK).
Setting:
Tokyo Medical and Dental University Hospital, Tokyo, Japan.
Methods:
The corneal surface was cooled before, during, and after laser ablation using a method called cooling PRK. Thirty-eighty highly myopic eyes of 38 patients whose spherical errors ranged from -8.00 to -18.75 diopters (D) were randomized into 2 groups: 16 eyes with conventional PRK and 22 eyes with cooling PRK. Postoperative pain was measured using the Visual Analogue Scale (VAS). Refraction, visual acuity, and complications were followed for up to 2 years. All data were analyzed and compared between groups to evaluate the cooling effect on PRK.
Results:
One day postoperatively, patients in the cooling PRK group had significantly less pain (P < .01). At 3 months, the haze score in the cooling PRK group was significantly less than in the conventional PRK group (P < .01). The residual refractive error was not significantly different between the 2 groups until 2 years, when it was greater in the conventional PRK (mean -5.09 D +/- 2.11 [SD]) than the cooling PRK group (-4.64 +/- 2.27 D). Ten eyes (62.5%) in the conventional PRK group and 15 eyes (68.2%) in the cooling PRK group were within +/- 1.00 D of the intended refraction. There were no serious complications in the cooling PRK group. Two eyes in the conventional PRK group had severe corneal haze and lost 2 Snellen lines of best corrected visual acuity.
Conclusion:
Corneal cooling on PRK effectively reduced postoperative pain, corneal haze, and myopic regression.
