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Zhuolin Liu, Anant Agrawal, Osamah Saeedi, Daniel Hammer; Adaptive optics imaging of retinal glia cells in patients with primary open angle glaucoma. Invest. Ophthalmol. Vis. Sci. 2019;60(11):019. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Early treatment is essential to manage glaucoma disease progression which manifests as damage to ganglion cell (GC) somata and axons. Activated microglia appear early in the glaucomatous process, suggesting that retinal glia cells may be a sensitive indicator of early glaucoma. Most knowledge about glia cell (i.e., microglia and astrocyte) function has come from animal studies, but how this knowledge applies to human retina remains elusive. In this study, we used adaptive optics - optical coherence tomography (AO-OCT) to investigate glia cell density changes in glaucoma.
Two eyes in two glaucoma subjects (P1: advanced glaucoma, 54 yrs and P2: mild glaucoma, 57 yrs) with hemifield defect and one age matched control eye (C1: control, 49 yrs) were imaged with the FDA multimodal AO imager. In the glaucoma subjects, three locations were imaged with the AO focus set to the inner retina: one above and one below the raphe in the approximate location of maximum and minimum retinal thickness as determined from clinical OCT collected prior to AO imaging (within 3-4° of the fovea); and a third location on the raphe at 12° temporal. In the healthy control subject, AO-OCT volumes were acquired from the fovea to 12° temporal retina at an interval of 1.5°. Up to 30 volumes (lateral dimension: 1.5×1.5°) were collected and registered in three dimensions. Glia cells present at the inner limiting membrane were counted from the en face projections at all imaged locations.
There was a large variation in the glia cell density distribution among the three subjects imaged in this study. In C1, there were no glia cells within 7.5° from the fovea, and the cell density increased from 17 cells/mm2 at 9° to 46 cells/mm2 at 12°. The results agree with previous observation. In P1, glia cells were not evident in any of the three locations examined. In P2, more glia cells were found at the location where the retina is relatively healthy (75 cells/mm2) than the inferior area affected by glaucoma (35 cells/mm2) and at 12° (52 cells/mm2).
The results indicate that the number of glia cells may depend on retinal location and disease stage. How glia density differs between glaucoma and healthy subjects may predict retinal health, given that the main function of those cells is to respond to pathological changes and keep the retina free of cell debris and remnants of dying cells.
This abstract was presented at the 2019 ARVO Imaging in the Eye Conference, held in Vancouver, Canada, April 26-27, 2019.
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