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Wendy Kirkland, Sung Chul Park, Rafael Furlanetto, Camila Netto, Yiyi Liu, Jeffrey Liebmann, Robert Ritch; In Vivo Dimensions of Schlemm’s Canal and Number of Collector Channels in the Nasal and Temporal Areas of Normal Eyes. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4850.
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© ARVO (1962-2015); The Authors (2016-present)
To determine if differences exist in the dimensions of Schlemm’s canal (SC) and the number of collector channels (CCs) between the nasal and temporal areas of normal eyes using in vivo enhanced depth imaging optical coherence tomography (EDI OCT).
Serial horizontal EDI OCT B-scans were obtained in the nasal and temporal limbal areas from one eye of each normal subjects (81 scans per 15x5 degree rectangle; interval between scans, ~35 µm; Fig A and B). The cross-sectional area of SC was measured in each EDI OCT B-scan (Fig C). After three-dimensional SC reconstruction, SC volume was calculated for the nasal and temporal areas. The CCs connected to the SC (Fig D) were counted in these areas. SC measurements and CC counting were performed by an independent observer, who was masked to the clinical information of the examined eyes.
Eleven normal eyes (11 subjects; mean age, 28±5 years) were included. The cross-sectional area of SC varied considerably within (mean of coefficients of variation of all eyes = 36%) and among the eyes (coefficient of variation of means of all eyes = 35%) (Fig E). The mean cross-sectional SC area was significantly greater nasally than temporally (3837±1397 µm2 vs. 3188±1204 µm2; p=0.034; Fig F), as was the SC volume (0.011±0.004 mm3 vs. 0.009±0.003 mm3; p=0.034). The SC cross-sectional area and volume were greater temporally than nasally in only one eye. The number of the CCs was significantly greater nasally than temporally (7.5±1.7 vs. 5.5±2.0; p=0.004; Fig G).
SC is larger with more CCs nasally than temporally in normal eyes. This may have important implications for the development of treatments that target the trabecular outflow pathway.
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