Laser in situ keratomileusis with the VISX Star laser for myopia over −10.0 diopters

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Abstract
Purpose: To evaluate the efficacy, predictability, stability, and safety of laser in situ keratomileusis (LASIK) for myopia over −10.00 diopters (D). Setting: The Eye Institute of Utah, Salt Lake City, Utah, USA. Methods: The prospective study included 332 eyes of 183 patients having LASIK with the VISX Star laser to correct myopia of −10.00 to −18.00 D. The eyes were divided into 3 groups according to the preoperative refraction: Group A (n = 208), −10.00 to −11.90 D; Group B (n = 94), −12.00 to −14.00 D; Group C (n = 30), −14.10 to −18.00 D. The mean follow-up was 12.0 months ± 5.6 (SD) (range 6 to 37 months). Results: Overall, the mean spherical equivalent decreased 96%, from −11.69 ± 1.46 D preoperatively to −0.37 ± 0.80 D postoperatively. The mean astigmatism decreased 72%, from 1.66 ± 1.22 D to 0.46 ± 0.53 D. At the last visit, 84.0% of eyes were within ±1.00 D of emmetropia and 96.4% were within ±2.00 D. An overcorrection of more than +1.00 D was experienced by 1.8% of patients. The uncorrected visual acuity (UCVA) was 20/20 or better in 45.8% of eyes and 20/40 or better in 89.5%. Six eyes (1.8%) lost 2 or more lines of best corrected visual acuity; this included 1 eye in which iatrogenic keratectasia developed 18 months after LASIK retreatment. Retreatment was done in 37.0% of eyes at a mean of 6.3 ± 5.3 months (3 to 32 months) after the initial treatment. At the last examination, 86.0% of eyes in Groups A and B and 70.0% in Group C were within ±1.00 D of emmetropia. A significant difference was found between Groups A and C (P = .032). The UCVA was 20/20 in 52.0% of Group A eyes, 38.0% of Group B eyes, and 23.0% of Group C eyes. The difference between Groups A and C was significant (P = .001), but the difference between Groups A and B was not (P = .055). Conclusions: In this study, LASIK was effective in correcting myopia up to −14.00 D. The efficacy, predictability, and safety were significantly less in eyes with myopia greater than −14.00 D.