Ocular Surface Changes in Eyes with Glaucoma Filtering Blebs

Purpose: To analyse the ocular surface changes in eyes with functioning filtering blebs and to correlate with the size of the bleb. Materials and methods: Forty eyes of 40 glaucomatous patients with functioning blebs and 40 normal control subjects underwent double vital staining for ocular surface evaluation, tear film break-up-time (BUT) and Schirmer I-test in a standardized fashion. Mann-Whitney U-test and Spearman's rank correlation were used to correlate bleb height and horizontal extent with BUT, Schirmer I-test, rose bengal and fluorescein staining scores. Results: Eyes with functioning blebs presented minimal, but significantly, higher rose bengal and fluorescein staining than controls (p < 0.000). The staining correlated poorly with the height and extent of the bleb. The Schirmer test in the study group showed greater measurements than controls, however, BUT showed shorter values in the study group as compared to controls (p < 0.05). Conclusion: Filtering blebs can interfere with the ocular surface stability causing few dry eyes like signs.