The preoperative intraocular pressure level predicts the amount of underestimated intraocular pressure after LASIK for myopia

Abstract

Aims: To evaluate the statistical significance of the parameters that affect underestimation of intraocular pressure (IOP) after laser in situ keratomileusis (LASIK) for myopia. Methods: In this prospective case series study, patient age, axial length, preoperative corneal curvature, preoperative central corneal thickness (CCT), preoperative IOP, and ablation depth were studied to determine whether they affect the underestimation of IOP in the right eyes of 100 consecutive patients who underwent LASIK. Results: The preoperative IOP was the most important parameter for an amount of underestimated Goldmann applanation tonometric IOP (GAT) and non-contact tonometric IOP (ncIOP) at 1 month (r = 0.654, p,0.0001, R 2 = 0.427, and r = 0.694, p,0.0001, R 2 = 0.481, respectively) and 3 months (r = 0.637, p,0.0001, R 2 = 0.406, and r = 0.726, p,0.0001, R 2 = 0.527, respectively). Patient age was statistically significant for underestimating the GAT at 1 month, and both the ablation depth and CCT were statistically significant parameters for underestimating the ncIOP at 1 month and at 3 months by stepwise multiple regression analysis (F.4.000). However, these parameters had small bivariate correlation coefficients, and were considered as minor parameters. Conclusion: Preoperative IOP is the most important parameter that affects an underestimation of IOP after LASIK for myopia. Eyes with a higher true IOP have a larger underestimation of the IOP after LASIK for myopia. From these results, the importance of the modulus of elasticity on IOP measurements was discussed.

Effect of laser in situ keratomileusis on rebound tonometry and Goldmann applanation tonometry

“…Thus, preoperative IOP measured by rebound tonometry could help predict the amount of IOP decrease after LASIK. 2 Although rebound tonometry is significantly correlated with CCT in normal eyes 7,26 and in eyes with glaucoma, [9][10][11][12]27 multivariate analyses found that the corneal biomechanical properties of corneal hysteresis (CH) and the corneal resistance factor (CRF) play a more significant role in rebound tonometry. 7,28 Corneal biomechanics are also important contributing factors that affect IOP measurement with other tonometers.…”

“…1,2 To prevent misdiagnosing an eye with glaucoma as being normal because of an artificially low IOP finding, accurate IOP measurement is important in patients having LASIK, particularly in a population with a high prevalence of myopia. 3 The gold standard for IOP measurement is Goldmann applanation tonometry.…”

Evaluation of corneal hysteresis and corneal resistance factor after corneal cross-linking for keratoconus

“…Certain surgical procedures, and a series of corneal diseases, are associated with substantial changes in the corneal tissue structure, and prospectively with altered biomechanical properties [1][2][3][4][5].…”

Intraocular pressure assessment in both eyes of the same patient after laser in situ keratomileusis

“…1 An association between primary open-angle glaucoma and myopia has been reported. 2 Accordingly, IOP evaluation is important for evaluating myopic patients after LASIK.…”