Corneal sensitivity and ocular surface health in patients undergoing femtosecond LASIK retreatment for residual refraction

Purpose: To assess corneal sensitivity and the ocular surface in patients undergoing primary femtosecond laser in situ keratomileusis (FS-LASIK) and those undergoing FS-LASIK retreatment under the same flap due to residual refractive error. Setting: Ekol Eye Hospital, Izmir, Turkey. Design: Prospective case series Methods: Nineteen patients with previous FS-LASIK who had myopic and astigmatic refractive error were included in the study group, and 19 age- and sex-matched patients undergoing FS-LASIK for the first time as the control group. Corneal sensitivity, Schirmer test, tear film break-up time (TBUT), Oxford grading scheme for ocular surface staining, and Ocular Surface Disease Index (OSDI) were measured preoperatively and at postoperative 1 week and 1, 3, and 6 months. Results: The mean refractive correction in the study and control groups respectively was 2.18±0.78 D (range: 1.00-3.50) and 2.76±1.20 D (range: 1.00-4.50; p=0.07). Corneal esthesiometry results in the study and control groups respectively were 6.10±12.55 vs. 9.90±11.50 mm at 1 week (p=0.001), 41.95±6.98 vs. 45.09±5.88 mm at 1 month (p=0.004), 56.09±3.37 vs. 56.19±2.52 mm at 3 months (p=0.8), and 58.60±2.01 vs. 58.80±1.39 mm at 6 months (p=0.5). Significant difference between the two groups in Schirmer test score that disappeared at postoperative 3 months and in TBUT and ocular surface staining that disappeared at 6 months, whereas the statistically significant difference in OSDI score persisted at 6 months (p=0.03) was detected. Conclusion: Corneal surface sensitivity and ocular surface health are more impaired in patients undergoing FS-LASIK retreatment due to residual refractive error.