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M Nishikawa, K Okazaki, E Chihara, Y Honda; The Changes of Intraocular Pressure and Corneal Structure After Laser in Situ Keratomileusis . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2117.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate the changes of intraocular pressure (IOP) and corneal structure after laser in situ keratomileusis (LASIK). Methods: Fifty myopic and astigmatic Japanese patients (100 eyes), eighteen (36 eyes) of which underwent LASIK, were included in a preoperative and postoperative study respectively. IOP was measured by applanation and noncontact tonometer. The corneal topographic images were obtained by Orbscan Corneal Topography System. Measurements were made before the surgery and 1 week, 1 month and 3 months postoperatively, except for applanation tonometry that was measured only 1 and 3 months after surgery to avoid trauma to the flap. Statistical analysis was performed with the Pearson correlation coefficient and the ANOVA. Results: In the pre-LASIK 100 eyes, positive correlations were found between applanation tonometry and noncontact tonometry; noncontact tonometry and central corneal thickness (CCT) (p= 0.001); and applanation tonometry and corneal curvature (p= 0.0065 and p= 0.0068 in 3 and 5mm zones, respectively). In the post Lasik group, the differences (Δ;) of the refractive error (spherical equivalent), CCT, and corneal curvature in 3 and 5 mm zones between pre and postoperative at 1 week, 1 and 3 months were: 4.9±2.1, 4.5±1.9 and 4.5±2.0D; 53.4±36.7, 50.1±35.8 and 45.7±36.0µm; 3.1±1.2, 2.9±1.2, 2.8±1.1 and 1.2±0.8, 1.0±0.9, 0.9±0.8D respectively. In all of these parameters, pre and post LASIK differences were statistically significant (p <0.05), and the values tended to increase during follow-up. The decrease in intraocular pressure with noncontact tonometer was 6.1±3.0, 5.8±2.8 and 6.0±2.4 mmHg at 1 week, 1 and 3 months post surgery. With applanation tonometer, the differences were 4.3±3.0 and 4.5±2.7mmHg at 1 and 3 months. During the follow-up, the values of these parameters were constant or rather decreased. There was no positive correlation between Δ;IOP and neither Δ;corneal curvature nor Δ;CCT; and between postoperative applanation and noncontact tonometry. Conclusion: After LASIK, the CCT, corneal curvature and spherical equivalent tended to increase, probably due to wound healing processes. However, the IOP showed a constant and decreasing tendency, thus, the changes in IOP did not reflect changes in corneal structure. This finding suggests the presence of multifactorial parameters which affect the IOP measurement.
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