Prospective randomized study of corneal aberrations 1 year after radial keratotomy or photorefractive keratectomy.
OBJECTIVE
To evaluate the optical properties of the cornea 1 year after either radial keratotomy (RK) or photorefractive keratectomy (PRK) in a randomized group of patients with low myopia.


METHODS
Ninety-six patients with myopia between -0.75 and -5.00 D were randomized to either radial keratotomy (n = 46) or photorefractive keratectomy (n = 50). Topography maps were obtained 1 year after surgery and analyzed by computation of total corneal wavefront aberration and Zernike polynomial coefficients for pupil sizes of 2, 4, and 6 mm. The 4-mm pupil size was used for optimization of the model.


RESULTS
The total corneal wavefront aberrations after RK and PRK were similar and not statistically different. Wavefront aberrations arising from astigmatism or defocus accounted for approximately 70% of the total wavefront error at all pupil sizes in both groups. All types of aberrations, and in particular spherical aberration, increased significantly with increasing pupil size. Higher-order wavefront aberrations were almost twice as high after RK than after PRK at pupil sizes of 4 and 6 mm. Spherical aberration and coma were slightly higher after PRK than after RK.


CONCLUSIONS
Pupil size had a major effect on corneal aberrations after RK and PRK. The most important aberrations were sphero-cylindrical, in which eyes became significantly more myopic with increasing pupil size. The image forming properties of the cornea are better after PRK compared with RK due to the lesser amount of higher-order aberrations.
Hjortdal
Jesper Ø
JØ
Department of Ophthalmology, Arhus University Hospital, 8000 Arhus C, Denmark. jesper.hjortdal@dadlnet.dk
Olsen
Hanne
H
Ehlers
Niels
N
D000328:Adult; D001251:Astigmatism / Q000175:diagnosis / Q000209:etiology; D019781:Corneal Topography; D005260:Female; D006801:Humans; D007646:Keratotomy, Radial / Q000009:adverse effects; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology / Q000601:surgery; D018903:Photorefractive Keratectomy / Q000009:adverse effects; D011446:Prospective Studies