RESUMEN
we analyzed data from 102 patients(152 eyes) who underwent photorefractive keratectomy to investigate the postoperative causes of unsatisfactory unaided visual acuity. A VISX 20/20 exicimer laser(VISX, Inc, Santa Clara, DA USA, version 4. 01) was used in all cases by one surgeon(J.W.H). The patients who showed unsatisfactory unaided vision, less than 20/40 uncorrected visual acuity, with minimal follow-up periods of 6 months were included. A decreased unaided visual acuity was detected in 20 eyes(13%). Range of preoperative myopia was -2.50 to -14.00 diopters. Mean postoperative uncorrected visual acuity(geometric mean)was 0.33+/-0.12 and mean corrected visual acuity was 0.83 +/-0.25. Multiple factors contributed to unsatisfactory unaided vision; myopic regression in 8 eyes, irregular astigmatism in 4 eyes, overcorrection in 1 eye, severe corneal opacity in 1 eyes(2.6%) and the causes were as follows; irregular astigmatism, decentration combined with central island and severe corneal opacity. In conclusion, refractive results after photorefractive keratectomy were reasonably predictable and stable, but some sight threatening complications occured in a minority eyes. Improved techniques such as centering procedures and improved excimer laser program will be essential to prevent unsatisfactory unaided vision.