Medium And Long-Term Outcomes Of Laser In-Situ & Undersurface Of Flap Keratomileusis For Ametropia

OBJECTION: To evaluate the medium and long-term efficacy of Laser in-situ & undersurface of flap keratomileusis(LASUK) for ametropia in eyes with thin corneal thickness or high myopia . And compare the medium and long-term outcomes and complications of LASUK with LASIK. Then help to investigate the efficacy, predictability, security, stability and the indications of LASUK.DESIGN: Retrospective cohort study.METHODS: Retrospective medical records from 106 patients (173 eyes) with high myopia with or without thin corneal thickness who underwent LASUK which were divided into 3 groups by diopter degrees: -6.00D≤Group 1 <-10.00D,-10.00D≤Group 2 <-15.00D,-15.00D≤Group 3≤-23.50D, and 77 patients (135eyes) who underwent LASIK which were divided into 2 groups by diopter degrees: -6.00D≤Group 1 <-10.00D, -10.00D≤Group 2 <-15.00D. All the surgeries were done in the ophthalmology center of the second affiliated hospital of Chongqing medical university. Data regarding age, gender, uncorrected visual acuity(UCVA), best-corrected visual acuity (BCVA), diopter degrees , corneal thickness, Anterior surface cornea curvature, Posterior surface cornea culmination curvature, incidence rate of Haze, surgical complications, and follow-up interval were collected from all visits and were analyzed.Compare the efficacy, security, stability, predictability and the indications of LASUK with LASIK. Data was Followed-up for 12 months to 40 months, with the average of 22.53 months.RESULTS: 1,The postoperative visual acuity after LASUK improved significantly, P<0.001, and the preoperative and postoperative UCVA changes at each time point was basically a growing trend. 2,When the refractive state stabilized one year after surgery, the diopter degrees of Group 1 was﹢0.63±1.28D, Group 2 was﹢0.75±1.28D, Group 3 was﹣0.01±1.78D.While two years after surgery, Group 1 was﹢0.18±0.96D, Group 2 was﹢0.15±1.37D, Group 3 was﹣0.11±1.69D,which were all in the range of±0.50D. 3,The thickness of corneal stroma bed after LASUK for Group 1 was 246um~358um,with the average of 291.48±26.52um, Group 2 was 245um~338um, with the average of 284.83±22.50um, Group 3 was 243um~371um, with the average of 280.45±26.58um,with no surgery-related complications or significantly increasing of posterior corneal surface curvature which means the new surgery have good predictability and security .4,Corresponding groups'diopter degrees and uncorrected visual acuity after LASUK had no significant difference compared with the ones after LASIK. 5,At the point of 3 months and one year after surgery, the anterior corneal surface curvature of which underwent LASUK was lower than that of LASIK, the difference is significant, P <0.05. 6,At the point of 1 months,3 months, 6 months and one year after surgery, the center of posterior corneal surface curvature of which underwent LASUK was significantly lower than that of LASIK, P <0.05,which means the posterior corneal surface after the surgery of LASUK is more stable than that after LASIK.CONCLUSIONS: 1,LASUK is an effective, safe, stable and predictable refractive surgery. 2,LASUK can achieved surgery results similar with LASIK. 3,Compared with LASIK, it's more secure, and stable to chose LASUK to treat ametropia in eyes with thin corneal thickness or high myopia.