Anmar Abdul-Rahman, William Morgan,Martin Hazelton, Brigid Betz-Stablein, Dao-Yi Yu,Geoff Chan4, Jonathan Lam

Purpose:
To describe results of a novel, non-invasivetechnique to objectively assess the distribution ofretinal vascular pulse waves in a group of normal sub-jects. Such technique may be useful in assessment ofvenous occlusion and glaucoma.

Materials and methods: Fourteen patients (22eyes) underwent retinal photo-plethysmography withand without ophthalmodynamometry (ODF) usingour in-house developed system. Pixel by pixel analysisof pulsatility timed to the cardiac cycle generates pul-sation amplitude values calculated using Fourieranalysis. These values were analysed by their distancefrom the optic disk centre in terms of disk diameter units.

Results: A total of 28,090 points were sampled fromboth retinal vascular systems (venous = 15,020, arte-rial = 13,070). The mean Fourier Amplitude (FA) wasgreater in the venous system 5.58 95% CI (5.49–5.67)compared to the arterial system 4.01 95% CI (3.93–4.09), p < 2.2e-16.The FA frequency distribution was skewed to the leftin both vascular systems and demonstrated a decreasein skewness at higher ODF values (p value = 0.001).The mean distance of the peak venous FA was reducedin ODF (0.34) compared to non-contact assessment(0.70), p-value = 0.002. Fourier amplitude diminishedalong the vessel from centre to periphery for both veinand artery (Spearman Rank: rho venous = ?0.37, arte-rial = ?0.26, p < 2.2e-16). Conclusions: This work describes the normal patternof retinal vascular pulsation and characteristic attenu-ation features, which are amplified by ophthalmody-namometry. Retinal image heat maps will be shownalong with alterations from normal seen in venousocclusion.