Analysis on the refraction change of high and super high myopia 6 years after LASIK

Objective To observe the diopter and height of cornea posterior surface of high and super high myopia patients after LASIK. Methods The data of 103 eyes of 58 cases with high and super high myopia 6 years after LASIK were collected.Before LASIK all cases of spherical equivalent refraction were - 6.00 D to-18.00 D. There were 40 eyes of 21 cases male and 63 eyes of 37 cases female.The age range was from 20 to 41 years, average was (25.06±7.51) years. The uncorrected visual acuity, best corrected visual acuity, diopter, corneal curvature , axial length and cornea posterior surface height at 1 month and 6 years after surgery were recorded. Results Six years after operation, the uncorrected visual acuity ≥0.8 occupyed for 69.70%.Diopter of myopia under -1.00 D occupyed for 75.75% and under -2.00 D in 90.9%.Corneal posterior surface height was (1.25±3.72) μm. No corneal posterior surface expansion happened .The average axial length was ( 26.84±1.31) mm.The difference was not statistically significant between before and after surgery (P=0.051). The postoperative best corrected visual acuity wasn’t impaired. The safety index was 1.19 and the efficacy index was 0.98. Conclusion After long-term observation, LASIK surgery is effective to high myopia and super high myopia .No corneal posterior surface expansion or secondary keratoconus happened. Key words: Myopia, high, super high; LASIK; Diopter change; Long-term