Posters

Changes in corneal asphericity and spherical aberration after laser insitu keratomileusis

Poster Details

First Author: M.Elkateb EGYPT

Co Author(s): M. Sabry                    

Abstract Details

Purpose:

To evaluate the changes of corneal asphericity and spherical aberration after laser insitu keratomileusis using scheimpflug imaging.

Setting:

Alex I-Care center , Alexandria, Egypt

Methods:

This prospective non randomized study included 170 myopic eyes and 30 hyperopic eyes. All patients had wavefront-optimized LASIK using the EX-500 machine (wavelight, Alcon). Patients within ±0.50 diopter of plano and with an uncorrected distance visual acuity of at least 20/20 were evaluated. The Q values and corneal spherical aberration Zernike values were obtained using Scheimpflug imaging (Oculyzer II) preoperatively and 1 to 3 months postoperatively.

Results:

The mean Q value was −0.28 ± 0.11 (SD) and −0.22 ± 0.15, respectively, preoperatively and +0.35 ± 0.44 and −0.64 ± 0.31, respectively, postoperatively. The asphericity change was highly correlated with preoperative spherical equivalent (r2 = 0.81; P≤.001). The mean corneal spherical aberration was +0.21 ± 0.08 μm in myopic eyes and +0.36 ± 0.11 μm in hyperopic eyes preoperatively and +0.36 ± 0.17 μm and 0.00 ± 0.29 um. There was a tendency for Q values and spherical aberrations to become more positive after myopic ablation and more negative after hyperopic ablation.

Conclusions:

Myopic and hyperopic corrections induced changes in the Q value and spherical aberrations in opposite directions (ie, positive and negative, respectively). The changes depended on the magnitude of the refractive correction.

Financial Disclosure:

None