Safety and predictability of laser in situ keratomileusis enhancement by flap reelevation in high myopia

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Abstract
To evaluate the safety and predictability of laser in situ keratomileusis (LASIK) retreatment following primary procedures for high myopia and astigmatism. Corneal Diseases and Excimer Laser Research Unit, Department of Ophthalmology, University of Dundee, Dundee, United Kingdom. This prospective observational study of retreatment comprised a cohort of 109 eyes having primary LASIK for high myopia and astigmatism with a spherical equivalent (SE) of −9.70 diopters (D) ± 4.06 (SD). Twenty-four eyes (22%) with an initial myopic SE of –9.83 ± 3.50 D, a comparable subset of the entire group (P < .05), had retreatment for residual myopia (−3.02 ± 2.17 D) to improve uncorrected visual acuity (UCVA) by reelevating the corneal flap and ablating the stromal bed. The mean follow-up after retreatment was 12.8 ± 5.1 months (range 1.5 to 24 months; 19 eyes ≥6 months, 13 eyes ≥12 months). The mean myopic SE was reduced to +0.53 ± 0.62 D at 1 week, +0.05 ± 0.50 D at 1 month, +0.30 ± 0.50 D at 6 months, and +0.18 ± 0.42 D at the latest follow-up, 12.8 months. At the latest review, 62% of eyes were within ±0.50 D of emmetropia and 100% were within ±1.00 D. The mean refraction did not alter statistically between 1 week and subsequent times. The mean UCVA improved from 6/30 prior to retreatment to 6/9 at the latest follow-up. Uncorrected visual acuity of 6/6 or better, 6/9 or better, and 6/12 or better was achieved by 33.0%, 75.0%, and 95.8% of eyes, respectively. No significant complications that led to a loss of best corrected visual acuity were encountered, although retreatment procedures were more uncomfortable than primary procedures and self-limiting; epithelial ingrowth that did not threaten vision was common, and 2 patients complained of nighttime visual symptoms. Retreatment of residual myopia by reelevating the flap was relatively safe and predictable, with a low risk of sight-threatening complications. However, longer term studies may be required to detect late complications.