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Hae Won Jung, Kazuhiro Kurokawa, John Hinely, Furu Zhang, Yan Liu, Marcel Trerice Bernucci, James A Crowell, Donald Thomas Miller; Spatial dynamics of inner retinal neurons in arcuate scotomas of glaucomatous subjects. Invest. Ophthalmol. Vis. Sci. 2020;61(7):229.
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© ARVO (1962-2015); The Authors (2016-present)
Glaucoma is characterized by the loss of ganglion cells (GC). Clinical OCT and visual fields can detect moderate to severe stages of glaucoma, but early detection of the disease is paramount before significant GC loss occurs. Recent advances in high-resolution retinal imaging using adaptive optics optical coherence tomography (AO-OCT) have enabled individual GC layer (GCL) somas to be visualized and quantified in humans, enabling the possibility for exquisitely early detection of glaucoma. In this study, we used AO-OCT to characterize the spatial dynamics of GCL somas in subjects with glaucoma.
Two patients with primary open-angle glaucoma and arcuate scotomas (P1: 73 and P2: 63 yrs old) participated in the study. Using clinical OCT and visual fields as guides, three adjacent locations traversing into the arcuate scotoma (5-7° nasal-inferior to the fovea, 1.5° square fields) and one location at the opposing hemifield were imaged with the Indiana AO-OCT system. We acquired 10-15 volume videos of each location, registered the volumes, and averaged them to improve soma contrast. Individual somas were manually identified from the averaged volumes to obtain soma density and size. To correct for inter-subject variability, the density and size measurements were normalized to those measured at the opposing hemifield location.
We found GCL soma density decreases with arcuate severity. For P1, soma density traversing into the arcuate defect decreased from 11,675, to 3,020, and to 1,801 somas/mm2, which corresponded to 48.3%, 86.6%, and 92.0% loss compared to that of the opposing hemifield (22,602 somas/mm2). The loss for P2 was more severe. Soma density extending into the arcuate defect was 900, 983, and 75 somas/mm2, respectively, which corresponded to 96.6%, 96.2%, 99.8% loss compared to the opposing hemifield (26,078 somas/mm2). GCL somas in the arcuate defect were significantly larger in their en face dimensions (p<0.01, One-way ANOVA) and appeared smaller in their depth compared to somas in the opposing hemifield. Prevalence of somas in the arcuate defect was positively correlated with size, suggesting that either larger somas are more apt to survive or somas enlarge or alter shape with the severity of the disease. In severely damaged areas, somas clustered around vessels.
AO-OCT reveals substantial GCL soma loss and size change in the arcuate scotomas of glaucomatous subjects.
This is a 2020 ARVO Annual Meeting abstract.
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