Purchase this article with an account.
Ariel Gelman, Lihua Gong, Elliott D. K. Cha, Mark Johnson, Haiyan Gong; Comparison of Schlemm’s Canal Giant Vacuoles between Eyes with Primary Open Angle Glaucoma and Age-matched Normals. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3467.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Previous studies have found that Schlemm Canal (SC) endothelial cells are stiffer in eyes with primary open angle glaucoma (POAG) compared to normal eyes (Overby, PNAS, 2014), suggesting that giant vacuole (GV) formation may be impaired in POAG. One study (de Kater, ARVO 1989) previously examined GV density in human eyes and found GV density was not reduced in POAG. However, whether the size of GVs is decreased in POAG eyes has not been examined. In this study, we compared both density and size of GVs between POAG and age-matched normal eyes.
Outflow facility was measured in 5 POAG eyes and 6 age-matched normal enucleated human eyes. The eyes were then perfused with fluorescent tracer and fixed at 15mmHg. Frontal sections were cut and imaged with a confocal microscope. Sections were assigned into active or inactive flow regions based on the amount of fluorescent tracer visible along the trabecular meshwork and inner wall of SC. Sections were prepared for light microscopy. Size of the vacuoles (including cross-sectional area, perimeter, major, minor axis and Ferret’s diameter), open and total SC length, and density (#of GVs per open SC length or per total SC length) were determined using Image J. A t-test was used for statistical analysis.
Outflow facility was significantly reduced in POAG eyes compared to normal eyes (p<0.01). Eyes with POAG showed a higher percentage of collapsed SC compared to normal eyes (p<0.02). There were no significant differences in GV density or size comparing POAG to normals and no difference was seen between active and inactive flow regions (p>0.15). There was also no difference in either normal or in glaucomatous eyes of GV density or size comparing the active to the inactive flow regions (p>0.25).
GV size and density did not differ in POAG as compared to age-matched normals in eyes perfusion-fixed at 15 mmHg. A lower, more physiological pressure drop (IOP–episcleral venous pressure) may allow differences in glaucomatous vacuoles to be detected. The similarity in vacuolar density and size in active and inactive flow regions suggests that giant vacuoles may not serve as markers for regions of active flow, as was previously suggested (Parc, IOVS, 2000).
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
This PDF is available to Subscribers Only