Purpose. The aim of the non penetrating filtering surgery is the
selective ablation of the external portion of the trabecular meshwork (TM)
which is involved in the aqueous outflow resistance. We evaluated, with a
confocal microscope, the structural characteristics of this part of the TM in
glaucomatous patients.
Methods. 60 external trabecular membranes (ETM) were obtained from 57
consecutive POAG patients and from
8 post-mortem normal age-matched donors who underwent a sclerectomy with
external trabeculectomy (ETM)in order to obtain satisfactory aqueous flow
through the remaining internal TM layers. After fixation and immunostaining
with anti-vimentin antibodies, the samples were analyzed with a confocal
microscope (Nikon EZ 2000).
Results. The mean thickness of the glaucomatous ETM was 33.7 ± 7.6 µm
(34.4 ± 10.4 µm for the controls, NS). Their main characteristic was a
significant paucicellularity as compared to the controls (respectively: 17.6 ±
10.5 and 167.5 ± 24.8 cells/ 2500 µm2). Their structural characteristics showed
involvement of both the cribriform and the corneoscleral trabecular layers.
Conclusions. These results confirm the previous reported
histopathological changes of the glaucomatous TM. The thickness and the
structural characteristics of the removed ETM suggest that the aqueous outflow
resistance is not restricted to the juxtacanalicular meshwork..