Histological Examination of Filtering Blebs With the in vivo Confocal Microscope

Abstract

Purpose: : To investigate the architecture of filtering blebs after trabeculectomy by in vivo laser confocal microscopy as well as slit-lamp.Patients: 17 eyes of 12 patients (8 males, 4 females) with functioning blebs in whom the intraocular pressure was under 20mmHg were included in this study.

Methods: : After a detailed slit-lamp examination including Seidel test, we examined the filtering blebs by in vivo confocal microscopy (Rostock Cornea Module/Heidelberg Retina Tomograph 2). Density of epithelial cell and microcysts was counted by cell counter program of Rostock Cornea Module. The details of surgical procedures and medications and clinical course of each patient was recorded in detail.

Results: : 17 eyes of 12 patients were examined 2 months to 170 month after final trabeculectomy (mean 72 months). The final surgical procedures included trabeculectomy with mitomycin-C (13 eyes), trabeculectomy with 5-FU (3 eyes), and trabeculectomy without antiproliferatives (1 eye). The duration after final surgery was 72.8+/-70.8 month. There were 8 leaking blebs all of which had a positive Seidel test. Other 9 eyes had no bleb leaks. In vivo confocal microscopy showed 20-50µm microcysts in the vicinity of the wall of all filtering blebs. The density of the microcyst was 6.7+/-5.3 /mm². Conjunctival epithelial density was 2574+/-1035 cells/mm². There was no statistically significant relationship between the duration after last surgery and epithelial cell density (P=0.85). The density of microcysts also didn’t have statistically significant relationship to post-surgical duration. Between cell density and microcyst density, there was a negative correlation, but it wasn’t significant (r=-0.41, P=0.10). On the other hand, bleb leak was significantly related both to cell density (P<0.01) and to microcyst density (P<0.01). No adverse events were observed due to in-vivo scanning in this study.

Conclusions: : In vivo confocal microscopy was a safe and an efficient method to investigate the structure of filtering blebs. Density of microcysts in blebs and the conjunctival epithelial density may be important in relation to pathogenesis of bleb leakage.

Keywords: imaging/image analysis: clinical • pathology: human