Evaluation of Ocular Surface Disease in Patients with Glaucoma

Abstract

To evaluate the subjective and objective measures of ocular surface disease in patients with glaucoma. Cross-sectional study. Sixty-four glaucoma subjects with bilateral visual field (VF) loss and 59 glaucoma suspects with normal VFs. Consecutive patients were recruited prospectively from the Wilmer Eye Institute Glaucoma Clinic. Tear film breakup time (TBUT), corneal staining score (0-15), and Schirmer's test results were included as objective metrics, whereas the Ocular Surface Disease Index (OSDI) questionnaire was administered to assess symptoms. Total OSDI score, vision-related subscore (derived from questions about vision and task performance), and discomfort-related subscore (derived from questions about ocular surface discomfort) were calculated for each subject. Seventy-five percent (48/64) of glaucoma subjects and 41% (24/59) of glaucoma suspects were receiving topical medications. The corneal staining grade was greater in glaucoma subjects than in glaucoma suspects (6.4 vs. 4.1; P<0.001), but groups did not differ with regard to TBUT or Schirmer's results (P>0.20 for both). Multivariate regression models showed that topical glaucoma therapy burden was associated with a significantly higher total corneal staining grade (β, +0.9 for each additional glaucoma drop; 95% confidence interval [CI], 0.5-1.3; P<0.001), but not with TBUT or Schirmer's results (P>0.20 for both). Glaucoma subjects had significantly higher total OSDI scores than glaucoma suspects (16.7 vs. 7.9; P<0.001). This largely was the result of higher vision-related subscores in the glaucoma group (11.1 vs. 3.3; P<0.001). Ocular discomfort-related subscores, however, were similar in both groups (5.7 vs. 4.6; P = 0.30). In multivariate analyses, each 5-decibel decrement in better-eye VF mean deviation was associated with a 4.7-point increase in total OSDI score (95% CI, 1.9-7.5; P = 0.001) and a 3.7-point increase in the vision-related subscore (95% CI, 1.7-5.6; P<0.001) but did not predict a higher discomfort-related subscore (β, 1.1 point; P = 0.07). Topical glaucoma therapy burden was not associated with higher total OSDI score or vision- or discomfort-related subscore (P>0.20 for all). Glaucoma is associated with significant ocular surface disease, and topical glaucoma therapy burden seems predictive of corneal staining severity. However, OSDI is a poor metric for capturing ocular surface disease in glaucoma because symptoms seem to be related largely to VF loss.