The causes of Unsatisfactory Unaided visual Acuity after Exximer Laser PRK for Myopia.

Cho, Seong Won; Hong, Jong Wook

Original Article

Journal of the Korean Ophthalmological Society 1998;39(9):1921-1928.
Published online September 1, 1998.

The causes of Unsatisfactory Unaided visual Acuity after Exximer Laser PRK for Myopia.

Seong Won Cho, Jong Wook Hong

Department of Ophthalmology, College of Medicine, Korea University, Seoul, Korea.

굴절교정 레이저 각막절제술후 낮은 나안시력의 원인

조성원(Sung Won Cho),홍종욱(Jong Wook Hong)

Abstract

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.

Key Words: Central islands;Decentration;Geometric mean;Irregular astigmatism;Unsatisfactory vision