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PURPOSE: To study the ocular surface in filtering blebs using impression cytology, comparing the bleb side and areas outside the bleb edges. METHODS: Twelve filtering blebs of 8 patients were included: 4 cases of trabeculectomy without mitomycin C (MMC), 6 cases of trabeculectomy with MMC, and 2 cases of non-penetrating glaucoma surgery. Impression cytology specimens were taken from filtering blebs as well as outside the bleb area. A classification scale from 0 to 3 was used to describe the distribution of epithelial cells and the density of goblet cells. Grade 0 indicated cohesive epithelial cells and abundant goblet cells; and the grade 3 indicated loss of epithelial cohesion and absence of goblet cells. RESULTS: The mean grade of cytology in filtering blebs was 2.4 ± 0.9, and in the outside bleb area of 0.8 ± 0.3 (P<.001). These differences were independent of the use of MMC (P=.48). The large majority (83%) of filtering blebs showed a decrease in epithelial cohesion and absence of goblet cells. Outside the bleb area, 100% of the cases had cohesive epithelial cells with different grades of goblet cells. CONCLUSION: The conjunctival epithelium overlying the filtering blebs showed significant changes that consisted of increased intercellular spaces and loss of goblet cells. These increased intercellular spaces could explain the trans-epithelial pathway of aqueous humor. The least amount of mucin due to loss of goblet cells could contribute to increase the risk of infection in filtering blebs.
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2.1 Conjunctiva (Part of: 2 Anatomical structures in glaucoma)
12.8.1 Without tube implant (Part of: 12 Surgical treatment > 12.8 Filtering surgery)