Abstract
Abstract: :
Purpose: Disruption of the anterior refracting surface of the eye (i.e., the tear layer) reduces visual performance. Tear layer break up occurs soon after a blink in contact lens wearers and dry eye patients. This study determined if artificial tears stabilize the tear film and improve visual performance in contact lens wearers who also exhibit a mild to moderate dry eye. Methods: Five subjects with complaints of mild to moderate dry eye (due to evaporative dry eye) during spectacle and contact lens wear were fitted with a Focus Night & Day hydrogel lens for this study. A temporal, 2–alternative, forced choice paradigm was employed to measure contrast sensitivity. The stimuli were vertically oriented sine wave gratings (between 0.5 and 14 cpd) presented for 16.67 msecs. The stimuli were presented at two different times after blink detection: 2 seconds after blink detection (i.e., before tear layer break up) or 4 seconds after tear film break up. Four conditions were investigated at 4 seconds after tear layer break up; 1) without artificial tears added, 2) with Clerz2 (Alcon), 3) with Sensitive Eyes (Bausch & Lomb) or 4) with GenTeal (Novartis) applied. The artificial tears were instilled at 10 minute intervals during the data collection. The short term visual effects of drop instillation were also investigated by continually monitoring contrast sensitivity for a 14 cpd grating after a single drop administration. Results: High spatial frequency contrast sensitivity and visual acuity were found to be reduced following tear film break up in the absence of supplementation with artificial tears. For the group data (and 4 out of 5 subjects), the instillation of B & L Sensitive Eyes improved the contrast sensitivity and visual acuity to the level attained before tear break–up, thus prolonging visual performance. Clerz2 and GenTeal did not produce any enhancement in visual performance. A short term decrease in contrast sensitivity was also observed with a single administration of Clerz2 and Genteal. Conclusions: This study indicates that there was a benefit of B & L Sensitive Eyes tear supplementation on visual performance in subjects with an evaporative dry eye. This may be due to 1) aqueous supplementation in these subjects and 2) the minimal tear layer disruption found with B & L Sensitive Eyes drop administration. The results suggest that practitioners need to identify those patients who can benefit from the use of appropriate artificial tear supplements.
Keywords: cornea: tears/tear film/dry eye • contrast sensitivity • cornea: clinical science