July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Density and volume of giant vacuoles with and without pores in the inner wall endothelium of Schlemm’s canal with increasing pressures
Author Affiliations & Notes
  • David L Swain
    Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
    Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts, United States
  • Thuy Duong Le
    Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
  • Beatriz Fernandes
    Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
  • Himeno Yamada
    Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
  • Ganimete Lamaj
    Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
  • Senila Yasmin
    Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
  • Indira Dasgupta
    Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
  • Haiyan Gong
    Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
    Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts, United States
  • Footnotes
    Commercial Relationships   David Swain, None; Thuy Duong Le, None; Beatriz Fernandes, None; Himeno Yamada, None; Ganimete Lamaj, None; Senila Yasmin, None; Indira Dasgupta, None; Haiyan Gong, None
  • Footnotes
    Support  NH Grant EY02234 and the Massachusetts Lions Eye Research Fund
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 2187. doi:
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      David L Swain, Thuy Duong Le, Beatriz Fernandes, Himeno Yamada, Ganimete Lamaj, Senila Yasmin, Indira Dasgupta, Haiyan Gong; Density and volume of giant vacuoles with and without pores in the inner wall endothelium of Schlemm’s canal with increasing pressures. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2187.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Giant vacuole (GV) volume is hypothesized to be one factor contributing to pore formation in inner wall endothelial cells of Schlemm’s canal (SC). Traditional scanning electron microscopy cannot distinguish cell nuclei from GV in SC endothelium accurately, and GV volume has not yet been studied. This study aimed to investigate whether there are changes in density and volume of GV with pores and without pores with increasing perfusion pressure and whether GV volume with pores is larger than that without pores in the inner wall endothelium of SC using serial block-face scanning electron microscopy (SBF-SEM) and 3D reconstruction.

Methods : Six normal human donor eyes were perfused at three different pressures (7, 15, and 30 mmHg, 2 eyes at each pressure). A small radial wedge of trabecular meshwork including SC was dissected from each eye (range of inner wall surface area: 0.0191 to 0.0397 mm2) and processed for SBF-SEM. More than 1000 serial images (section thickness = 0.13 µm) were analyzed per wedge. GV and pores were labeled. Using Reconstruct, GV were traced, reconstructed in 3D, and volumes with or without pores were determined and compared. Statistical analysis was performed using R.

Results : At 7mmHg (physiological pressure in enucleated eye), GV density was 9914 GV/mm2, the density of GV with pores was 1644/mm2 and mean GV volume was 109.4 ± 13.0 µm3 (mean ± SEM; N = 121). Density of GV with pores was higher in 15 mmHg (2034 of 10566 GV/mm2), and lower in 30 mmHg (918 of 7144 GV/mm2). The percentage of GV with pores significantly increased in 15 mmHg (24.6%; 114/507; P<0.01) and 30 mmHg (12.8%; 46/356; P = 0.018), compared to 7mmHg (9.6%; 69/758). GV volume was significantly increased in 15 (196.3 ± 33.8 um3; N = 156) and 30 mmHg (196.6 ± 24.3 um3; N = 102) (ANOVA, P<0.05). The volume of GV with pores was significantly larger than GV without pores at 15 mmHg (P<0.01). GV with pores at 15 mmHg were larger than those at 7 mmHg (P<0.05).

Conclusions : SBF-SEM provided an accurate method to quantify the GV density, volume, and percentage of GV with pores. GV volume was significantly increased at higher pressure. GV with pores were significantly larger than GV without pores only in 15mmHg, not in 7 and 30mmHg, suggesting other factors than GV size may influences pore formation. Further investigation of factors that regulate pore formation is needed.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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