Abstract
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....