Abstract
M.Phil.
The anterior surface of the eye, especially the corneal curvature, is of
importance in optometric and ophthalmic examinations. Pathological, surgical
and contact lens induced changes to the cornea can have a significant
influence on vision. It is therefore necessary to study the structure, curvature,
and factors that influence the cornea. Each study contributes to a greater
understanding about the nature of the anterior surface of the eye.
Previous studies showed that physical exercise has an effect on the eye.
These studies however looked at changes in intraocular pressure, visual
acuity and other visual functions due to exercise. No study was found in the
literature that investigated the effect of exercise on keratometric variation or
on corneal curvature. A study done by Cronje-Dunn (1995) suggested the
possibility of exercise influencing keratometric variation and the mean
keratometric measurement. Due to little research in this area and the
suggestions that exercise might influence keratometric variation, it was
decided to investigate the influence of physical exercise on keratometric
variation.
In this study, 14 subjects took part in an experiment. The experiment
consisted of three sets of keratometer readings obtained for each subject.
The first set of readings was obtained before exercise. Directly after the first
set of keratometer readings, the subject had to reach 85% of his predicted
maximum heart rate on a stationary bicycle. Immediately after the cycling the
second set of keratometric readings was obtained. After the second set of
measurements the subject rested for an hour. The third set of keratometric
readings was obtained after the hour of rest. The different sets of
keratometric measurements were converted to h vectors. Transforming
keratometric readings to h vectors and plotting the readings on threedimensional
graphs representing symmetric dioptric power space make it
possible to view the distribution or spread of the keratometric measurements
and to define any variation in the measurements.
The results from this dissertation indicate that keratometric variation and
corneal curvature was influenced by physical exercise (cycling). Exercise
increased variation in curvature around the vertical meridian and/or increased
torsional variation in the horizontal and vertical meridians for most subjects.
The increase in variation in curvature after exercise was greatest between the
80° and 120° meridian of the eye. This increase in keratometric variation after
the cycling decreased after the rest period in most subjects. Little change in
variation was noted in the curvital power around the horizontal meridian.
Some subjects indicated a change in mean. The mean was greater around
the vertical meridian either after the exercise and/or after the rest period.