Changes in contrast sensitivity function and ocular higher order aberration by conventional myopic photorefractive keratectomy.
OBJECTIVE
To evaluate the relation between induced changes in ocular higher order aberrations and changes in the contrast sensitivity function in patients undergoing excimer laser photorefractive keratectomy (PRK).


METHODS
Myopic PRK using excimer laser was performed in 31 patients (56 eyes). The preoperative refractive error was -6.2 +/- 2.9 diopters. Before and 1 month after surgery, we measured the ocular higher order aberrations for a 4-mm pupil, and three indices of contrast sensitivity function. From the data collected, the area under the log contrast sensitivity function (AULCSF) was calculated.


RESULTS
PRK significantly reduced AULCSF (P = 0.004), low-contrast visual acuity (P = 0.004), and letter-contrast sensitivity (P = 0.013). Coma-like (P < 0.001) and spherical-like (P < 0.001) aberrations were significantly increased by surgery. The change in AULCSF by surgery significantly correlated with the change in coma-like (r = -0.468, P < 0.001) and spherical-like (r = -0.291, P = 0.033) aberrations. The change in low-contrast visual acuity by PRK significantly correlated with the change in coma-like aberration (r = 0.599, P < 0.007), but not with change in spherical-like aberrations (r = 0.136, P = 0.326). There were significant correlations between changes in letter-contrast sensitivity and changes in coma-like (r = -0.450, P < 0.001) and spherical-like (r = -0.255, P = 0.048) aberrations.


CONCLUSIONS
PRK significantly increases ocular higher order aberrations, which compromise contrast sensitivity function after surgery.
Sakata
Norishige
N
Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan.
Tokunaga
Tadatoshi
T
Meiwakai Medical Foundation, Miyata Eye Hospital, Miyazaki, Japan.
Miyata
Kazunori
K
Meiwakai Medical Foundation, Miyata Eye Hospital, Miyazaki, Japan.
Oshika
Tetsuro
T
Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan. toshika@md.tsukuba.ac.jp.
D000293:Adolescent; D000328:Adult; D001251:Astigmatism / Q000503:physiopathology* / Q000601:surgery; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology* / Q000601:surgery; D018903:Photorefractive Keratectomy / Q000379:methods*; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology*; D016896:Treatment Outcome