Abstract
Abstract: :
Purpose: Previous studies indicate that artificial tears can decrease contrast sensitivity in spectacle wearers. Artificial tears can interact with contact lens materials and result in tear layer distortion which further decreases contrast sensitivity. The purpose of this study is to investigate if artificial tears have a greater effect on contrast sensitivity in contact lens vs. spectacle wearing subjects. Methods: Twenty normal subjects took part in this project. Ten subjects were habitual SCL wearers and ten were habitual RGP lens wearers. The artificial tears used were Celluvisc (1.0% high-viscosity CMC; Allergan) and Liquigel (1.0% blended medium and high-viscosity CMC; Allergan). Each subject was examined under four experimental conditions, 1. CL + Celluvisc, 2. CL + Liquigel, 3. Spectacles + Celluvisc, and 4. Spectacles + Liquigel. Each condition was run on a separate day and the order was random. 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 threshold over time. After baseline data collection, a drop of the artificial tear was applied to the tear layer and the procedure continued for 30 minutes. This allowed continual tracking of the threshold. Results: For all experimental conditions, after the artificial tear was placed on the eye, there was a significant decrease in contrast sensitivity that lasted several minutes (all p values < 0.05). The magnitude of this decrease in contrast sensitivity was not significantly different between the CL and Spectacle wearing conditions for either artificial tear (all p values > 0.05). Furthermore, there was no difference in the length of time this decrease in sensitivity lasted for the CL and Spectacle wearing conditions (all p values > 0.05). Conclusions: The results indicate that a single application of Celluvisc or Liquigel does not adversely interact with the CL material to magnify the loss in contrast sensitivity. Future studies need to determine if similar effects are seen when other types of artificial tears are employed.
Keywords: cornea: tears/tear film/dry eye • contrast sensitivity • cornea: clinical science