Objective: To analyze the aberration of human eyes after LASIK by using wavefront analyzer, to evaluate the eye aberrations by using the large spot in refractive surgery, and to compare the aberrations in different pupil zones.
Methods: This is a prospective clinical study. Preoperatively and postoperatively, uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), spherical equivalent (SE) and aberrations were evaluated on each patient. The patients were divided into three different groups according to the SE diopter before the surgery. We used the SAS and SPSS10.0 statistic software to analyze the data.
Results: Preoperatively, BCVA was 4.98 +/- 0.07. Ten days after surgery, UCVA and BCVA were 4.92 +/- 0.10 and 4.95 +/- 0.09, respectively. One month after surgery, UCVA and BCVA were 4.96 +/- 0.09 and 4.99 +/- 0.09, respectively. Over time, visual acuity improved with Postoperatively, parts of the eye's BCVA were better than preoperatively. Ten days after LASIK, the SE of three groups were hyperopic. But with time, SE changes to myopia. In the Allegretto exam, high order aberrations increased immediately after surgery in each group (P < 0.05), but decreased with time (P > 0.05) and did not return to preoperative values at one month. Preoperatively, the total aberrations (RMSg) were larger than postoperatively. The aberrations especially spherical are larger in the 6.5 mm pupil zone than in the 4 mm pupil zone. Preoperatively, there were no significant differences of high order aberrations between the three groups (P > 0.05). But after surgery, there were significant differences (P < 0.05).
Conclusions: Initially, high order aberrations increased after LASIK, but decreased over time. Preoperatively, there were no significant differences of aberrations between the three groups, but after surgery, significant differences existed. The aberrations especially spherical were larger in the 6.5 mm pupil zone than in the 4 mm pupil zone. Allegretto wave-front analyzer can be used for low to middle myopia.