Abstract
Purpose: :
To evaluate the long–term outcome of photorefractive keratectomy (PRK).
Methods: :
Thirty patients (20 male, 10 female) were recruited. PRK was performed between 1992 and 1993. Seventeen (56.7%) had PRK in both eyes, thirteen (43.3%) in one eye for a total number of 47 eyes. The mean age was 30.9 ± 7.5 (range 19–47). Preoperative mean spherical refraction was –4 ± 1.8 D (range: –0.75 –10.8 D) and the mean astigmatism was 1.1 ± 0.4 D (range 0.25–3). Preoperative uncorrected mean visual acuity (UCVA) was 0.12 ± 0.1 (range 0.02–0.5) and best corrected VA (BCVA) was 0.97 ± 13 (range 0.5–1.1). All patients had normal corneas. PRK was performed with a SUMMIT Technology excimer laser; optical zone was 5 mm. Postoperative follow–up was scheduled at 1 day, 3–6 days and 1, 3, 6, 12, 18, 24 months and then every 2 years. Complete dilated eye examinations were performed with special attention to corneal status and refraction.
Results: :
All patients achieved their BCVA within three months after PRK and remained substantially stationary. At 13 years mean spherical refraction was –0.4 ± 0.8 D and mean astigmatism was 0.4 ± 0.6 D. Mean UCVA was 0,87 ± 0,3 (range 0.2–1.1) and BCVA was 0.94 ± 0.2 (range 0.3–1.1). Only 1 eye (2.1%) had a decrease in BCVA. Corneal haze mean score was 0,9 at 1 month and 0,5 from 3 to 12 months. At 13 years 1 patient (3.3%) had haze of grade 0.5. Three eyes (6.4%) had raised IOP after PRK; at 13 years, no patient had glaucoma. After 13 years the integrity of cornea was preserved in all patients and there was no evidence of corneal ectasia. None had developed retinal tears or macular pathology. Three patients (6.4%) needed some lachrymal substitute due to a dry eye condition without any evidence of ocular surface disease.
Conclusions: :
To our knowledge, this prospective study has the longest follow–up available on myopic PRK. Refractive status achieved at 3 months was maintained up to 13 years with no evidence of late regression. Corneal haze decreased with time, with complete recovery of BCVA. No late complications were found in this study. Our results confirm other shorter studies and demonstrate the efficacy and safety of myopic PRK.
Keywords: refractive surgery: PRK • myopia • visual acuity