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Abstract #18971 Published in IGR 3-1
Deep non penetrating sclerectomy with external trabeculectomy: an evaluation with the confocal microscope
Hamard P; Sourdille P; Valtot F; Baudouin CJournal Français d'Ophtalmologie 2001; 24: 29-35
PURPOSE: Deep non-penetrating sclerectomy (DNPS) is a new filtering surgical procedure whose aim is a selective ablation of the external portion of the trabecular meshwork (TM) which is involved in aqueous outflow resistance, i.e., the inner wall of Schlemm's canal (SC) and the external trabecular layers, especially the cribriform TM. With a confocal microscope, the authors evaluated the structural characteritics of this part of the TM in glaucomatous patients. METHODS: Thirty-six external trabecular membranes (ETM) were obtained from 33 consecutive glaucomatous patients (mean age: 56.5 ± 14.5 years) and from four post-mortem normal donors (60.5 ±7.7 years), who underwent DNPS according to the same surgical procedure. Under conjunctival and scleral flaps, the roof of the SC was opened and removed. A deeper dissection led to the removal of the inner wall of the SC and the adjacent ETM, i.e, the TEM, which allowed a satisfactory aqueous flow through the remaining internal TM layers. After fixation with acetone or triton X100 and immunostaining with anti-fibronectin or vimentin antibodies, the samples were analyzed with a confocal microscope (Nikon EZ 2000). RESULTS: The mean thickness of the ETM was 34.4 ± 7.3 μm in glaucomatous eyes, not significantly different from the controls (39.0 ± 10.7 μm). The main characteristic of the glaucomatous ETM membrane is a paudcellularity compared to the controls (respectively 21.6(pi) 12.1 cells/area and 156.1 ± 28.8 cells/area). The confocal microscope analysis shows that the ETM involves two different portions of the trabecular meshwork. The architectural characteristics of the outermost portion of the ETM with its star-shaped cells arranged in a homogenous extracellular matrix, suggest that it is the trabecular cribriform meshwork. The inner portion of the ETM shows cells arranged regularly in a fibrillar extracellular matrix as described in the corneoscleral trabecular meshwork. CONCLUSIONS: These results confirm the previous reported histopathological changes of the glaucomatous TM. The thickness of the removed ETM and its structural caracteristics show that the ablation of the TM layers necessary to obtain a satisfactory aqueous filtration, not only involves the cribriform layers but also one of the inner parts of the TM, i.e., the corneoscleral TM. This result suggests that aqueous humor resistance not only involves the cribriform trabecular meshwork but also a part of the comeoscleral trabecular meshwork. LA: French
Dr P. Hamard, Centre du Glaucome, CHNO des Quinze-Vingts, 28 rue de Charenton, 75012 Paris, France
Classification:
3.2 Electron microscopy (Part of: 3 Laboratory methods)
