title: Diurnal variation in vision after radial keratotomy.
abstract: We tested eight patients who had undergone radial keratotomy with regard to refraction, keratometry, corneal thickness, and intraocular pressure one to two weeks after surgery. Patients were examined immediately after eye-lid opening at 7:30 A.M. and again at 4:00 P.M. The contralateral eye was used as a control. The treated eye was 1.48 +/- 0.24 diopters (mean +/- S.E.M.) more hyperopic at the morning examination compared to the afternoon visit, whereas the control eye had an insignificant shift (0.16 +/- 0.06 diopters). The treated eye was significantly flatter (1.37 +/- 0.19 diopters) in the morning than in the afternoon when compared to the control eyes, which were only 0.11 +/- 0.09 diopter flatter. The intraocular pressure changed insignificantly in both the treated and control eyes (-0.5 +/- 0.53 mm Hg and -0.5 +/- 0.84 mm Hg, respectively). The mean morning corneal thickness was significantly greater (5.7%) than the afternoon thickness when compared to the controls (1.7% morning increase in thickness). These data suggest that diurnal variation in corneal thickness after radial keratotomy plays a role in diurnal variation of vision in the early postoperative period.
authors.affiliation: Department of Ophthalmology, Oregon Health Sciences University, Portland.
authors.forename: S
authors.initials: S
authors.lastname: MacRae
authors.forename: L
authors.initials: L
authors.lastname: Rich
authors.forename: D
authors.initials: D
authors.lastname: Phillips
authors.forename: R
authors.initials: R
authors.lastname: Bedrossian
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D006801:Humans; D007646:Keratotomy, Radial / Q000379:methods; D011184:Postoperative Period; D014785:Vision, Ocular / Q000502:physiology*