M.Phil. (Optometry) / Previous studies of corneal and keratometric variation used incomplete or incorrect statistical methods. 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, trajectories of change in dioptric power, ellipsoidal confidence regions for mean dioptric power, as well as meridional profiles. Quantitative expressions of variation are given in terms of mean values, variance-covariance matrices and volumes of 95% distribution ellipsoids. Manual and automatic keratometry is compared, both on a steel ball and on an eye. It appears that the automatic keratometer exhibits less variation than the manual keratometer....
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:3726 |
| Date | 10 February 2014 |
| Creators | Cronje- Dunn, Sonja |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Johannesburg |
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