DEVELOPMENT OF VISUAL ACUITY IN THE EARLY PHASE FOLLOWING PHOTOREFRACTIVE KERATECTOMY FOR MYOPIA
N.X. Nguyen, A. Langenbucher, M.M. Kus, B. Seitz
Photorefractive keratektomy (PRK) using the excimer laser is an accepted surgical technique for correction of myopic refraction errors in case of spectacle or contact lens incompatibility. The purpose of this study was to assess the development of uncorrected (UVA) and best-corrected visual acuity (CVA) in the early phase following PRK.
Patients and Methods: 38 eyes of 26 patients that underwent photorefractive keratectomy using an 193 nm excimer laser (MEL 60, Aesculap-Meditec) were included in this study. The preoperative spherical equivalent was -5,3 ± 2,4 diopters (D) (range -1.75 to -9,5 D). Pre-, intra- and postoperative treatment was standardized. The median time interval until complete epithelial closure was 2 days. According to their spherical equivalent, patients were divided in two groups: group l with myopia = 6 D, group 2 with myopia more than 6 D.
Results: After surgery the UVA increased by 0.73 ± 0.25 lines, whereas the CVA increased by 0.05 ± 0.10. The UVA was stable after 3 months, the CVA was stable after 1 month (table). The difference comparing pre- and postoperative UVA was significantly higher (0.81 ± 0.22) in groupl than in group 2 (0.60 ± 0.26) (p = 0.004). However, CVA values were not significant different comparing the two group after 6 months (p = 0.07).
|Time||Preop||day 3||day 7||1 month||3 months||6 months|
l/20(LT in 1m)
Conclusion: Typically, useful uncorrected visual acuity is achieved at day 3 after PRK in eyes with mild to moderate myopia. With higher degrees of myopia the uncorrected visual acuity increases slower towards a lower level.
Department of Ophthalmology, University of Erlangen-Nürnberg, Schwabachanlage 6, D-91054 Erlangen, Germany