Abstract
Abstract: :
Purpose: Artificial tears when applied to the tear film alter its structure and may affect contrast sensitivity. Previous studies indicated that Liquigel and Celluvisc (not FDA approved for use with a contact lens) decreased contrast sensitivity in contact lens wearers. The purpose of this study was to investigate how the addition of FDA approved contact lens lubricants to the tear film affects contrast sensitivity over time. Furthermore, different tear formulations were investigated to determine if one formulation was best. Methods: Eight normal CL–wearing subjects took part in this project. Clerz 2 (Alcon), Focus Lens Drops (CIBA Vision), and Sensitive Eyes Drops (B&L) were investigated. The stimulus, viewed monocularly, was a stationary, vertically oriented, sine wave grating (14 cpd). A temporal, two–alternative, forced–choice paradigm combined with a self–paced method of limits was employed to monitor the threshold over time. After baseline data collection, a drop of the lubricant was applied to the tear film and the procedure continued for 30 minutes. This allowed continual tracking of the threshold for this period. Results: A significant decrease in contrast sensitivity occurred after the application of each of the lubricants (paired T–test, all P values < 0.05). There was no difference in the magnitude of the decrease in sensitivity between the three lubricants (all values P > 0.05). The duration of the decrease in sensitivity was not significantly different among the three lubricants tested (all P values > 0.05). Conclusions: The results indicate that there was no significant difference in the decrease in contrast sensitivity in either duration or magnitude among the contact lens lubricants tested. This was despite differences in formulations in the three lubricants. Clerz 2 contains a viscosity enhancer and a surfactant, Focus Lens Drops contains a surfactant and Sensitive Eye Drops contains neither. Thus, visual performance should not be a factor in the choice of any of these three contact lens lubricants.
Keywords: cornea: tears/tear film/dry eye • cornea: clinical science • contrast sensitivity