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.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:1756 |
| Date | 30 November 2011 |
| Creators | Du Toit, Ilse von Solms |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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