Visual Function and Tear Film Lipid Layer Stability in Patients With Dry Eye

Abstract

Purpose: : To test the hypothesis that patients with keratoconjunctivitis sicca (KCS) have a significant degree of visual function alterations and tear film lipid layer changes.

Methods: : Thirty patients (30 eyes) with dry eyes were identified on the basis of the typical symptoms measured by a validated questionnaire (OSDI Questionnaire Score >10), Schirmer I test scores < 10 mm/5 minutes, tear break-up time (BUT) < 7 seconds, lissamine green conjunctival staining > 3 (NEI grading system), and punctuate epithelial keratopathy. The dynamic lipid interference pattern test (DLIP) was used to measure tear lipid layer stability. Visual function was measured as distance contrast sensitivity by a letter chart, as near contrast sensitivity by means of a new test specifically developed for dry eyes, and by using a visual tracing test. A group of 30 healthy subjects (30 eyes) was used as control.

Results: : The DLIP test in the dry eye group (2.7 ± 2.0 blinks) was statistically decreased compared to the control group (17.8 ± 5.8 blinks, p< 0.0001, t-test). Patients with KCS showed a significant decrease of distance (p < 0.05) and near (p < 0.001) spatial-contrast sensitivity. A significant Pearson’s correlation (r = 0.61) was found between near spatial-contrast sensitivity and BUT. No differences were recorded in visual tracing tests performances.

Conclusions: : Tear film lipid layer changes and visual function alterations are characteristic of dry eye. Contrast sensitivity tests seem to be an important tool in our hands to measure quality of vision in KCS patients.

Keywords: cornea: tears/tear film/dry eye