Photoablation centration on the corneal optical center in myopic LASIK using AOV excimer laser

To evaluate the clinical efficacy of laser-assisted in situ keratomileusis (LASIK) with ablation centration on the corneal optical center with standard sphero-cylindrical ablation model.

A total of 119 eyes (60 patients) underwent primary myopic LASIK with standard sphero-cylindrical ablation model using AOV Excimer laser, and they were divided into 2 groups according to the ablation centration. The experimental group had 60 eyes (30 patients) with ablation centered on the corneal optical center and in the control group of 59 eyes (30 patients) ablation was centered on the pupil center. Patients' basic characteristics were evenly matched. The distance between ablation center and corneal vertex normal (DAV) was measured to describe the match of ablated tissue and virgin cornea. The uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, and higher-order aberrations (HOAs) for a 6-mm pupil area between the 2 groups were compared.

Mean DVA was 0.35+/-0.15 mm in the experimental group versus 0.69+/-0.23 mm in the controls, and the difference between the two groups was significant (p<0.05). No significant difference was found in postoperative UCVA and BSCVA between the 2 groups (p>0.05). A total of 90% of eyes in the experimental group had residual astigmatism within 0.5 D versus 72.88% eyes in the control group, and the difference was significant (p<0.01). The increase of root mean square of HOAs was smaller in the experimental group (p<0.01), as compared to the control group.

The corneal optical center serving as the ablation center in LASIK with standard sphero-cylindrical ablation model may be superior to the entrance pupil center.