Effect of artificial tears on visual performance in subjects with dry eye

Disruption of the anterior refracting surface of the eye (i.e., the tear layer) reduces visual performance. Tear layer breakup occurs soon after a blink in contact lens wearers and patients with dry eye. This study determined whether artificial tears stabilize the tear film and improve visual performance in contact lens wearers who also exhibit a dry eye.

Five subjects with mild to moderate dry eye (probably as a result of an evaporative dry eye) during spectacle and contact lens wear were fitted with a Focus Night & Day hydrogel lens for this study. A temporal, two-alternative, forced-choice paradigm was used to measure contrast sensitivity. The stimuli were vertically oriented sine wave gratings (between 0.5 and 14 cpd) presented for 16.67 msec. The stimuli were presented at two different times after blink detection: 2 sec after blink detection (i.e., before tear layer breakup) or 4 sec after tear film breakup. Four conditions were investigated at 4 sec after tear layer breakup: 1) without artificial tears added, 2) with Clerz2 (Alcon, Fort Worth, TX) instilled, 3) with Sensitive Eyes (Bausch & Lomb, Rochester, NY), and 4) with GenTeal (Novartis, Basel, Switzerland) applied. The artificial tears were instilled at 10-min 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.

High spatial frequency contrast sensitivity and visual acuity were found to be reduced after tear film breakup in the absence of supplementation with artificial tears. For the group data (and four of five subjects), the instillation of Sensitive Eyes improved the contrast sensitivity and visual acuity to the level attained before tear breakup, 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.

This study indicates that there was a benefit of Bausch & Lomb Sensitive Eyes tear supplementation on visual performance in subjects with an evaporative dry eye. This may be the result of 1) aqueous supplementation in these subjects and/or 2) the minimal tear layer disruption found with 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.