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. 2000 Dec;84(12):1354–1359. doi: 10.1136/bjo.84.12.1354

Morphological variability of the trabecular meshwork in glaucoma patients: implications for non-perforating glaucoma surgery

T Dietlein 1, P Jacobi 1, C Luke 1, G Krieglstein 1
PMCID: PMC1723341  PMID: 11090472

Abstract

BACKGROUND/AIMS—Morphological variability of the trabecular meshwork could be of considerable importance for the proper intraoperative outcome of non-perforating antiglaucomatous surgery, such as deep sclerectomy and viscocanalostomy. The aim of this study was therefore to assess qualitative and quantitative characteristics of the trabecular meshwork in glaucoma patients undergoing trabeculectomy.
METHODS—Trabeculectomy specimens from 177 glaucoma patients were prepared for light microscopy; 100 specimens were found to be suitable for qualitative assessment and quantitative computerised image analysis; measurements were taken of the meridional diameter of Schlemm's canal as well as the thickness of the trabecular meshwork at different positions.
RESULTS—The mean meridional diameter of Schlemm's canal was 290 µm with the smallest values in the young patients with infantile and secondary glaucomas. the thickness of the trabecular meshwork ranged between 50-70 µm in the anterior region and between 100-130 µm for the posterior portion. The thickness of the anterior meshwork significantly decreased with age. The pigmentation of excised trabecular meshwork was found to be weak or even lacking in 68 patients. In 20 glaucoma patients the uveal meshwork was covered by an endothelial layer.
CONCLUSIONS—From the morphological point of view the risk of inadvertent perforation during deep sclerectomy in older, white glaucoma patients should be taken into account even by an experienced surgeon, because the anterior meshwork in these cases is very thin and trabecular pigmentation that can be used as a topographic landmark is often lacking. The functional success of non-perforating glaucoma surgery in many patients may be limited by endothelial covering of the trabecular meshwork.



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Figure 1  .

Figure 1  

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Trabecular meshwork in a 67 year old patient with primary open angle glaucoma revealing no pigmentation. The broken line shows the meridional diameter of Schlemm's canal (SC), lines 1-4 indicate the positions where the thickness of the trabecular meshwork was measured. Original magnification ×134.

Figure 2  .

Figure 2  

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Linear regression line with 95% CI describing the relation between age and thickness of the trabecular meshwork at position 1: slope is −0.44 (0.11); r2=0.16; p<0.0001.

Figure 3  .

Figure 3  

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Linear regression line with 95% CI describing the relation between age and thickness of the trabecular meshwork at position 2: slope is −0.42 (0.15); r2=0.07; p=0.006.

Figure 4  .

Figure 4  

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Linear regression line with 95% CI describing the relation between age and thickness of the trabecular meshwork at position 3: slope is −0.07 (0.23); r2=0.001; p=0.75.

Figure 5  .

Figure 5  

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Linear regression line with 95% CI describing the relation between age and meridional diameter of Schlemm's canal: slope is 1.3 (0.44); r2=0.09; p=0.004.

Figure 6  .

Figure 6  

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Trabecular meshwork in a 57 year old patient with irido-corneo-endothelial (ICE) syndrome and secondary glaucoma. The lumen of Schlemm's canal (SC) is bridged by several tissue bands. The uveal meshwork is completely covered by a thick endothelial layer (arrowheads). Original magnification ×309.

Figure 7  .

Figure 7  

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Trabecular meshwork in a 72 year old patient with primary open angle glaucoma and history of laser trabeculoplasty. Schlemm's canal (SC) consists of separated lumina; a radially running drainage vessel (DV) meets the anterior part of Schlemm's canal. The anterior meshwork shows a loss of intertrabecular space and an endothelial covering (arrows). Original magnification ×244.

Figure 8  .

Figure 8  

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Trabecular meshwork in a 65 year old patient with exfoliative glaucoma showing moderate pigmentation. A "bridge-like channel" (CH) goes tangentially along with Schlemm's canal (SC) proved by serial sections. Original magnification x 259. 

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These references are in PubMed. This may not be the complete list of references from this article.

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