Corneal Topography And Postoperative Outcome After Photorefractive Keratectomy And Laser In Situ Keratomileusis For Correction Of Myopia

Objective: To identify the associations of corneal topography and postoperative outcomes after photorefractive keratectomy(PRK) and laser in situ keratomileusis (LASIK)for correction of myopia. Method: A total of 151 patients(300 eyes) with preoperative refraction of -3.00D～-10.00D (-6.08±1.21)D were treated with PRK and LASIK and followed up for 12 months. The patients were divided into 2 groups: PRK group, 76 cases(150 eyes); LASIK group, 75 cases(150 eyes). Corneal topography was examined 1,3,6,12 months postoperatively,and associations with postoperative outcomes were analyzed. Result: 1. Corneal topographic patterns were classified as uniform, semicircular,keyhole, kidney, central island and irregularity after PRK and LASIK. There was no central island pattern after LASIK. 1, 3, 6, 12 months after PRK, 48.8%, 60.0%, 66.7% and 66.7% showed uniform respectively; 1, 3, 6, 12 months after LASIK, 80.0%, 90.0%, 90.0% and 90.0% showed uniform respectively. 3 months after surgery, corneal topographic patterns tended to be stable. Uniform pattern after LASIK was more than that of PRK (P<0. 01). There was statistical significant difference among the3percentage of corneal topographic patterns after PRK and LASIK (P<0.001). Patterns of both groups tended to become more regular. 2. Central island and irregularity patterns affected the postoperative uncorrected visual acuity (UCVA) greatly. UCVA after LASIK was better than that of PRK (P<0.05). 3. Decentration was similar after PRK and LASIK, there was no statistical significant difference between them (P>0.05). Decentration more than 0.50mm affected the postoperative UCVA greatly(P<0.001). 4. The change of SimK after LASIK was smaller than that of PRK (P<0.01). There was statistical significant difference among the change of SimK postoperatively(P<0. 05). Conclusions: 1 .Corneal topographic patterns were classified as uniform, semicircular, keyhole, kidney,central island and irregularity after PRK and LASIK. There was no central island pattern after LASIK. Corneal topographic patterns showed little change after 3 months postoperatively. Patterns of both groups tended to become more regular. Uniform pattern after LASIK was more than that of PRK, there was statistical significant difference. 2. Central island and irregularity patterns affected the postoperative UCVA greatly. UCVA after LASIK was better than that of PRK, there was statistical significant difference. 3. Decentration had no change with time. There was no statistical significant difference between PRK and LASIK. Decentration more than 0.50mm affected the postoperative UCVA greatly. 4. The change of SimK at different times postoperatively was different, there was statistical significant difference among them. The change of SimK after LASIK was smaller than that of PRK, there was statistical significant difference. SimK was important in predicting refractive regression.