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Sahar Shariflou, Kathryn Ailsa Rose, Ashish Agar, Mojtaba Golzan; Amplitudes of spontaneous venous pulsations are associated with retinal ganglion cell count estimates in glaucoma. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5064.
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Assessment of spontaneous venous pulsation (SVP) amplitudes are suggested to be a vascular biomarker for glaucomatous optic neuropathy (GON). There is evidence that reduced SVPs are associated with a thinner retinal nerve fiber layer (RNFL) and localized visual field defects. To investigate the link between SVP amplitudes and the structural and functional changes associated with GON, this study used a novel tool to examine the relationship of SVP amplitude to retinal ganglion cell (RGC) count.
25 participants (average age 73 ± 10 years; 13 males) with confirmed glaucoma (19) and suspected glaucoma (6) had intraocular pressure (IOP) measured (Goldmann), Humphrey Visual Field (HVF) testing and optic nerve imaging using optical coherence tomography (OCT, Spectralis). Following dilation (1% mydriacyl), a 10 second videoscopy of retinal circulation at the optic nerve head using a tablet-based ophthalmoscope was performed. RGC counts were estimated using HVF outputs and OCT RNFL thickness measures based on equations developed by Harweth et al.1 The SVP traces were extracted from the videos using a custom written algorithm. SVP amplitude was calculated as the percentile change in venous diameter (i.e. peak-trough/mean vein caliber). Linear regression was used to study the association between SVP amplitudes and RGC count estimates.
Mean IOP was 15 ± 3.90 mmHg and RNFL 78.08 ± 18.57µm. HVF data in glaucoma and glaucoma suspects had mean deviations of -3.26 and -2.44 respectively, compared to age-matched normative HVF data. SVPs were observed in 100% of participants with a mean SVP amplitude of 40.38% ± 10.41 and RGC count of 638997 ± 169897. We observed a positive and statistically significant association between SVP amplitudes and RGC counts, with reduced SVP amplitudes correlating with lower RGC counts (RGC=6441.8SVP+378893, p=0.05, r=0.395) (Figure 1).
This novel technique was able to detect SVPs in all subjects and we found a positive relationship between SVP amplitude and RGC count, indicating that SVPs could be a measure of structural and functional change in glaucoma. This technique could be developed for use in early detection and monitoring of structural and functional changes in GON.Reference1. Harwerth, R. S., et al. "Linking structure and function in glaucoma." Progress in retinal and eye research 29.4 (2010): 249-271.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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