Abstract
Purpose:
: Loss of spontaneous retinal venous pulsatility (SRVP) has been described as a new risk factor for glaucoma and its progression. In this study we investigate the magnitude of local SRVP’s and retinal venous pulsation pressure (VPP) and correlate these with glaucomatous damage in the same region.
Methods:
20 subjects with primary open angle glaucoma were studied. SRVP amplitude of superior and inferior hemiretinal veins was measured in all patients using the Dynamic Vessel Analyzer (DVA, Imedos). Ophthalmodynamometry (OcuDyn - Perth, WA) was performed to measure VPP in veins with absent visible pulsations. Sectoral RNFL thickness was recorded using Spectralis OCT (Heidelberg). Raw SRVP recordings were passed through a low pass filter (cut of frequency; 5Hz). For each individual, mean SRVP amplitude and then amplitude normalized for IOP (i.e. SRVP/IOP) were plotted against local RNFL thickness (superior and inferior sectors). VPP measurements were also plotted against SRVP amplitude and RNFL thickness.
Results:
SRVP was detectable and recordable from hemi-retinal veins in all subjects using the DVA, even though no visible SRVP was present in many cases (using 60D lens). Mean SRVP amplitude for all subjects was 3.9±2.2 um. SRVP amplitude correlated with RNFL thickness (r2=0.55), and when normalised for IOP was strongly correlated, with larger SRVP amplitudes observed in thicker RNFL (RNFL=108.1SRVP +42.4, r2=0.7). An inverse relationship occurred when comparing VPP to SRVP and RNFL thickness. Higher VPPs correlate with less SRVP amplitude (VPP=-3.5SRVP+45.9, r2=0.25) and thinner RNFL (VPP=-0.28RNFL+53, r2=0.3). The latter is expected as loss of SRVP at the disc should be associated with less pulsation in adjacent retinal veins. Both observations support a relationship between reduced venous pulsation and glaucoma.
Conclusions:
SRVP is present in all individuals; however the amplitude of pulsation is altered in glaucoma. Lower SRVP amplitude and higher VPP correlate with glaucoma severity. These dynamic parameters may be useful as novel biomarkers for glaucoma risk assessment.
Keywords: 568 intraocular pressure •
550 imaging/image analysis: clinical