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Anders Vestergaard, Jakob Grauslund, Anders Ivarsen, Jesper Hjortdal, Anne K. Sjolie; Long-term Outcomes Of Photorefractive Keratectomy For Low To High Myopia: Up To 19 Years Of Follow-up. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5571.
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Although surgical techniques are rapidly evolving, surface ablation of the cornea is by many still considered the overall safest procedure for treatment of low myopia. Our purpose with this study was to evaluate the long-term outcomes of excimer laser myopic photorefractive keratectomy (PRK), with the world’s longest follow-up study of PRK patients.
Retrospective study of the first cohort of PRK-treated patients in Denmark. Patients were treated with PRK at the Department of Ophthalmology, Odense University Hospital, in the period 1992 to 1995. All patients selected for surgery had stable myopia for at least one-year and no other ocular diseases or conditions. The same surgeon performed all surgical procedures with the same broad-beam laser (SVS Apex Laser system, Summit Technology, Inc.). In total, 230 patients between 19 and 30 years of age were retrospectively identified. Patients were invited to a follow-up eye examination including corneal tomography (Oculus Pentacam-HR Scheimpflug camera). Of the original cohort, 185 patients were invited. The rest (n=45) had died, moved abroad, or refused to participate.
In total, 107 patients (n=172 eyes) completed the follow-up 16 to 19 years after undergoing PRK. One hundred forty eyes had low myopia (<-6.0 diopters (D)), and 32 eyes had high myopia (≥-6.0 D). The pre-operative mean spherical equivalent (SE) refraction for all eyes was -4.4 ± 2.1 D (range -1.0 to -10.8 D). At follow-up, eyes with low myopia had a mean difference between attempted and achieved SE refraction of -0.7 ± 1.1 D (range +1.1 to -6.9 D), and eyes with high myopia was -1.2 ± 2.3 D (range +1.0 to -10.8 D) of target. For all eyes, 51 % were within ± 0.5 D of the target SE refraction, 74 % were within ± 1.0 D, and 91 % were within ± 2.0 D. Mean uncorrected distance visual acuity (UDVA) was 0.14 ± 0.33 logMAR (range 1.48 to -0.22 logMAR) and mean corrected distance visual acuity (CDVA) was -0.09 ± 0.09 logMAR (range 0.52 to -0.24 logMAR). Eight percent of eyes with low myopia, and 16 % of eyes with high myopia, had visible haze grade 0.5 to 2. Three percent of all eyes had undergone PRK re-surgery due to myopic regression. A total of 2 eyes had lost 2 or more lines of CDVA at follow-up, and 8 eyes had gained 2 lines. Mean central corneal thickness was 524 ± 34 µm (range 402-610 µm), and no signs of postoperative ectasia were noted, neither clinically nor tomographically.
Photorefractive keratectomy for low to high myopia is a safe and effective procedure in the very long-term, but with lower predictability and twice as high risk of haze amongst eyes with high myopia.
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