Abstract
Purpose: :
To evaluate and compare the effect of moderate myopic correction by laser-assisted in situ keratomileusis (LASIK) and laser epithelial keratomileusis (LASEK) on intraocular pressure (IOP) and to examine any correlation with ablative depth.
Methods: :
In a retrospective comparative case series of a clinic-based population undergoing elective moderate myopic correction, pre-operative, 1 month and 3 month post-operative central corneal IOP measurements by tonopen were reviewed in 35 eyes (19 patients) undergoing LASIK with the Bausch and Lomb XP Microkeratome and the Bausch and Lomb Technolas 100Hz Laser and 48 eyes (25 patients) undergoing alcohol-based LASEK with the same laser. Manifest refraction, ultrasonic central corneal thickness and ablative depth were also examined.
Results: :
The non-glaucomatous LASIK and LASEK groups had a mean pre-operative spherical equivalent of -5.09 ± 1.27D and -5.80 ± 1.25D, respectively. 91.4% of the LASIK eyes and 81.3% of the LASEK eyes showed a decrease in IOP after 3 months. The mean decrease in measured IOP was 3.8 ± 2.79 mmHg (p<0.001) in LASIK eyes and was 1.94 ± 2.91mmHg (p<0.001) in LASEK eyes. The greater degree of IOP reduction with the LASIK group compared to the LASEK group was statistically significant (p=0.004). Linear regression analysis of the decrease in IOP and ablative depth was not significant in either group.
Conclusions: :
Moderate myopic correction with both LASIK and LASEK results in significant IOP reduction by tonopen measurements. The greater degree of IOP reduction with the LASIK eyes was significant and is likely related to the influence of the lamellar corneal flap in addition to ablation. The insignificant relationship between IOP change and ablative depth may be due to the moderate myopic patient selection and overall deeper ablative depth. Post-operative management of both LASIK and LASEK patients should take into consideration this IOP reduction to avoid false low IOP readings.
Keywords: intraocular pressure • refractive surgery: LASIK • myopia