An assessment of the clinical effect of treatment for high myopia and ultra-high myopia 10 years after laser in situ keratomileusis

Objective To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) for high and ultra-high myopia 10 years after surgery. Methods In this retrospective study, 41 patients (80 eyes) who underwent LASIK from October 2002 to May 2004 for myopia were recently reexamined. Data for uncorrected visual acuity (UCVA) , refractive error, and best corrected visual acuity (BCVA) were evaluated as well as the degree of regression, the percentage of UCVA≥5.0, and loss of ≥2 lines of BCVA. Patients were divided into two groups based on average preoperative spherical equivalent: group A: -6.00~-10.00 D (44 eyes) and group B: >10.25 D (36 eyes). A t test was used for normally distributed data. Attributes data were analyzed using a χ2 test. A Pearson correlation coefficient was used for correlation analysis. Results A UCVA of ≥4.7 was achieved in 85% of the patients and ≥5.0 in 45% among the 80 eyes. No patients lost ≥2 lines of BCVA. The percentage of UCVA ≥1.0 in group A was significantly higher than that in group B (χ2=5.518, P<0.05). The mean spherical equivalent was -0.91±1.43 D 10 years after LASIK surgery, which differed significantly from the preoperative data of -10.10±2.42 D (t=-28.196, P< 0.01). The percentage of regression ≤0.50 D was higher in group A than group B (χ2=6.865, P<0.05). A regression ≥1.00 D was obtained in 30 eyes after 10 years. A positive correlation was found in these 30 eyes between the degree of regression and the difference between the actual and expected corneal thickness (r=0.706, P<0.01). Conclusion LASIK for high myopia is an effective and safe long-term procedure, but it is slightly less predictive in patients with ultra-high myopia. Key words: Keratomileusis, laser in situ; Myopia, degenerative; Therapy outcome