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Thesis

Effect of overnight wear of high and low water content hydrogel lenses on corneal topography

1 May 1994

Abstract

One eye of each of 11 subjects was fitted with Optima FW soft lenses (water content = 38%) while the contralateral eye was fitted with B&L 70 Minus soft lenses (water content = 70% ) on a extended-wear basis. Corneal topographic changes of each subjects were recorded by the EyeSys Corneal Analysis System (EyeSys Laboratories, Houston, TX) before and after wearing continuously for a period of seven days and seven nights. The results showed that there was no significant change in topography in eyes fitted with Optima FW lenses. On the other hand, there were significant flattening by 0.09mm ± 0.095mm of the average flattest meridian at the peripheral cornea (7mm zone) in the eyes fitted with B&L 70 lenses. The overall curvature was also flattened by 0.04mm ± 0.059mm than the baseline reading in the eyes fitted with the high water content lenses. The difference between the corneal curvature change of both lenses on the eyes were also found to be statistically significant. However,there was no significant change in subjective refraction in eyes fitted with both lenses. The possible explanations of these changes were discussed and suggestions were given for further investigation in this topic.


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