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C. R. Hann, A. J. Vercnocke, M. D. Bentley, E. L. Ritman, M. P. Fautsch; 3-Dimensional Analysis of Collector Channels in Normal and POAG Eyes. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2735.
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To determine whether collector channel structure differs between POAG and normal eyes.
The anterior segments of two pairs of normal human eyes (61F and 68F) and two pairs of glaucoma eyes (61M and 88F) were perfused at 10 mmHg with DMEM media for 2 hours. Eyes were perfusion fixed at 10 mmHg with 4% paraformaldehyde/2% glutaraldehyde for 8-12 hours. The anterior segment was divided into quadrants, immersed in 2% osmium tetroxide, dehydrated and embedded in Epon-Araldite. The nasal and temporal quadrants of each eye were scanned using 3-dimensional micro-computed tomography (3D-micro-CT) at 5 µm cubic voxel resolution. 3-D volume images of collector channels were evaluated using the software program ANALYZETM. Collector channel circumference was measured 30 µm and 50 µm from the collector channel orifice.
The number of collector channels in POAG and normal eyes was similar in both nasal (POAG=9; Normal=8) and temporal regions (POAG=7; Normal = 6). In the nasal quadrant, the mean collector channel orifice size was 48% narrower in POAG eyes when compared to normal (32.8 ± 8.3 µm, n=9, vs. 62.5 ± 16.7 µm; n=8, p=0.001). A similar trend was seen in the temporal quadrant where the POAG collector channel orifices were narrower by 45% when compared to normal (25.7 ± 12.7 µm, n=7 vs. 46.7 ± 23.4 µm, n=6, p=0.08). POAG collector channel circumference was reduced by more than 50% when compared to normal eyes (30 µm: 124 ± 101 µm, n=16 vs. 268 ± 120 µm, n=14, p<0.001; 50 µm: 104 ± 81 µm, n=16 vs. 245 ± 142 µm, n=14, p<0.002). The volume of the nasal and temporal quadrants of Schlemm’s canal was decreased in POAG eyes compared with normal: 0.006 ± 0.001 vs. 0.026 ± 0.008 mm3.
Collector channels within the nasal and temporal regions of POAG eyes have reduced orifice diameter and circumference when compared to normal. Schlemm’s canal volume was also reduced in POAG eyes. No difference in collector channel number was noted.
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