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Comparison of topographical changes associated with overnight wear of inverted silicone hydrogel contact lenses of different powers

1 May 2005


Purpose: Previously conducted studies have demonstrated significant topographical changes following overnight wear of both normally configured (non-inverted) and inverted -6.00D silicone hydrogel lenses. Further, a distinct difference in topography was realized between eyes wearing the inverted vs non-inverted lenses. These results suggest that silicone hydrogel lenses may be sufficiently rigid to potentially effect predictable changes in corneal topography following overnight wear. This investigation was designed to study the effects of overnight wear of -9.00D silicone hydrogel lenses to evaluate changes in corneal topography and to compare these results with previously collected data to determine if they result in greater changes in topography due to increased rigidity of the lenses.

Methods: Baseline corneal topography data was collected for N = 11 subjects. The subjects were then fit with -9.00D Focus Night & Day (CibaVision) silicone hydrogel lenses. All subjects, who were recruited based on their participation in the initial study, wore a non-inverted lens on one eye and an inverted lens on the other eye, to match the conditions of the previous study, which was determined by a randomization schedule. Lenses were removed following 12hrs of continuous wear, including 8hrs of overnight wear. Following removal of the contact lenses, corneal topography data was collected, and a comfort survey was completed comparing the subjects' perception of comfort with both the non-inverted and inverted contact lenses.

Results: The inverted -9.00D lens resulted in significantly (p

Conclusions: Greater corneal flattening was realized with inverted silicone hydrogel contact lenses vs non-inverted lenses. Further, the effect was greater with higher powered minus lenses. These data suggest that planned corneal reshaping to correct for refractive error may occur with appropriately designed silicone hydrogel lenses. Both inverted and non-inverted contact lenses were well-tolerated during overnight wear.


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