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Time course of corneal biomechanical parameters after laser in situ keratomileusis
Kazutaka Kamiya1, Kimiya Shimizu, Fumiko Ohmoto
1Department of Ophthalmology, University of Kitasato School of Medicine, Sagamihara, Kanagawa, Japan. kamiyak-tky@umin.ac.jp
Purpose:
To assess the time course of corneal biomechanics after laser in situ keratomileusis (LASIK).
Methods:
We examined 36 eyes of 20 consecutive patients undergoing LASIK for low to moderate myopia. We quantitatively assessed the values of corneal biomechanics characterized by corneal hysteresis (CH) and corneal resistance factor (CRF) using an Ocular Response Analyzer (Reichert Ophthalmic Instruments) before and 1 week, 1, 3, and 6 months after surgery. We carried out this measurement 3 times, and the average value was used for statistical analysis.
Results:
The CH was 10.6 +/- 1.7 (mean +/- SD) mm Hg preoperatively, and 8.6 +/- 1.2, 9.0 +/- 1.7, 9.0 +/- 1.4, and 8.9 +/- 1.5 mm Hg 1 week, 1, 3, and 6 months postoperatively, respectively. The CRF was 10.0 +/- 1.7 mm Hg preoperatively, and 7.3 +/- 1.5, 7.6 +/- 2.0, 7.8 +/- 1.6, and 7.7 +/- 1.6 mm Hg 1 week, 1, 3, and 6 months postoperatively, respectively. The variances of the data were statistically significant (p < 0.001 for both CH and CRF). Multiple comparisons demonstrated significant differences between measurements made before surgery and at all postoperative times (at 1 week and 1, 3, and 6 months; p < 0.001 for CH and CRF, Fisher's least significant difference test).
Conclusions:
Over the study period, the largest changes in corneal biomechanical parameters occurred within 1 week after surgery, and these then became nearly stable. No progressive deterioration of the corneal biomechanics was observed at any time during the 6-month follow-up period.
