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Estimation of IOP decrease after myopic (and astigmatic) LASIK based on spherical equivalent of manifest refraction and keratometry values

Poster Details

First Author: T.Bozkurt TURKEY

Co Author(s):    A. Bahadir Kilavuzoglu   C. Coşar   B. Şener        

Abstract Details


To quantitate the relation between manifest refraction, keratometry and intraocular pressure (IOP) change after myopic (and astigmatic) LASIK


Acıbadem University Medical Faculty Ophthalmology Department


Four hundred and twenty five eyes of 215 patients who had LASIK for myopia (and astigmatism) were enrolled in this retroprospective study. Preoperative spherical equivalent of manifest refraction (SEMR, attempted correction) and preoperative and postoperative keratometry values were recorded. IOP was measured using an air-puff tonometer before and 3 months after uneventful LASIK. Mean age of the patients was 32 ± 7.9 (range) years. Mean preoperative spherical equivalent of manifest refraction (SEMR) was -3.7 ± 1.7 [(-0.88)-(-9.38)] D. Mean preoperative and postoperative keratometry was 43.7 ± 1.5 (range) D and 40.5 ± 1.7 D (range), respectively with a mean keratometry change (Δ KM) of 3.1 ± 1.4 (range) D. Mean preoperative and postoperative IOP was 16.7 ± 2.9 (range) mmHg and 12.1 ± 2.1 (range) mmHg, respectively with a mean IOP change (Δ IOP) of 4.6 ± 2.3 (range) mmHg. The relationship between Δ IOP, ΔKM and preoperative SEMR were examined using Pearson correlation analysis.


There was a significant negative correlation between Δ IOP and SEMR (p<0.01). The regression coefficient was -0.54 suggesting that for each diopter of myopia treated by LASIK, IOP was measured 0.5 mmHg lower. Similarly, Δ IOP was positively correlated with Δ KM significantly (p<0.01).The regression coefficient was 0.67 suggesting that for each diopter of corneal flattening, IOP was measured 0.67 mmHg lower.


Present study suggested that the greater the SEMR corrected by LASIK and the greater the postLASIK flattening of corneal curvature, the higher the fall of IOP measured by air-puff tonometer after LASIK. Therefore, preLASIK SEMR as well as ΔKM might be used to estimate postoperative IOP after myopic LASIK. FINANCIAL INTEREST: NONE

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