title: Short-term keratometric variation in the human eye.
abstract: Previous studies of corneal and keratometric variation used statistical methods that were not entirely satisfactory. For the first time, proper multivariate statistical methods are applied to evaluate short-term keratometric variation in human eyes. Keratometric variation is represented graphically by means of stereo-pair scatter plots, ellipsoidal confidence regions for mean dioptric power, and meridional profiles of variation. There is great variability in the keratometric variation displayed by different subjects, although most subjects exhibit greatest variation in the vertical meridian of the eye on most of the measuring occasions. Variance-covariance matrices based on vector h are given. In some cases keratometric variation approaches neutral uniform variation. In many of the subjects, mean keratometric measurements change from morning to afternoon, usually showing an increase in curvature later in the day. Physical activity may increase keratometric variation and mean curvature.
authors.affiliation: Department of Optometry, Rand Afrikaans University, Johannesburg, South Africa. scr@rau3.rau.ac.3a
authors.forename: S
authors.initials: S
authors.lastname: Cronje
authors.forename: W F
authors.initials: WF
authors.lastname: Harris
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002940:Circadian Rhythm; D003315:Cornea / Q000033:anatomy & histology / Q000502:physiology; D006801:Humans; D008297:Male; D008433:Mathematics; D009907:Optometry / Q000379:methods*; D012029:Refraction, Ocular / Q000502:physiology*