An evaluation of orthokeratology.
Twenty-three orthokeratology (OK) patients and 16 cosmetic hard contact lens (CL) patients were evaluated. Initially, each patient underwent a complete examination including central and peripheral keratometry, specular microscopy, axial length determination, uncorrected visual acuity, and cycloplegic refraction. The patients were then re-evaluated every three months. When the retainer lens stage was reached, the contacts were removed, and the patients were again re-examined for six additional months. Nine of ten CL patients remained in the study, during which time there was no improvement in unaided visual acuity or spherical equivalent. Both the central horizontal and vertical meridians flattened during this time. Twenty of 21 OK patients were also studied. A different technique of fitting contact lenses was used for this group, which produced significant changes in uncorrected visual acuity (P > 0.01) and spherical equivalent (0.1 > P > 0.05), but not in the central or peripheral corneal curvature. Five of the OK patients failed to respond. Six had variable, unpredictable responses, and nine had good responses. Analysis of the information in this study demonstrates that an OK procedure utilizes techniques of fitting that differ from standard contact lens techniques. The responses to OK are unpredictable and uncontrollable. The quality of uncorrected vision is worse than with contacts or glasses, and the chances of attaining 6/12 (20/40) uncorrected vision are small. Once lenses are removed, the corneal parameters return toward prefit levels.
D000328:Adult; D003261:Contact Lenses / Q000592:standards*; D003315:Cornea / Q000502:physiology; D005069:Evaluation Studies as Topic; D005500:Follow-Up Studies; D006801:Humans; D011446:Prospective Studies; D012030:Refractive Errors / Q000175:diagnosis / Q000628:therapy*