Abstract
Purpose :
To describe pulse amplitude characteristics among eyes with central retinal vein occlusion (CRVO) and hemiretinal vein occlusion (HVO) at the optic nerve and peripapillary region.
Methods :
Ophthalmodynamometry was used to measure force projected on the eye while retinal video photography was simultaneously captured. This technique was used to measure photoplethysmography (PPG) estimates of blood column pulse amplitude. This was timed against cardiac cycle and utilised harmonic analysis at each 30x30 micron loci within 1.5mm from the disc centre. Maps of pulse amplitude change were constructed looking at upper and lower hemiretinal arteries and veins. The relationships between pulse amplitude, diagnosis and distance from optic disc centre were analysed using linear mixed modelling accounting for random factors for eye and person. Logarithm of pulse amplitude values were used as the response variable to normalise raw pulse amplitudes are right skewed.
Results :
107 eyes of 70 subjects (43 male, 27 female, mean age 64±18 years) were examined. 79 eyes were normal, 20 had CRVO, 8 with HVO including the corresponding unaffected 8 hemiretinal vessels from the same eye. Normal eyes had mean venous pulse amplitude 9.66±7.80u within 1.5 mm from the optic disc centre. Veins affected by CRVO had the lowest amplitude (3.16u±2.16u, p<0.0001) followed by hemiveins with HVO (4.58u±3.08, p<0.0001). Interestingly, the unaffected hemiveins in HVO eyes had a significantly lower amplitude as well (5.50u±4.14, p<0.0001). Similarly, the mean arterial amplitude was significantly reduced in other categories (CRVO: 2.84u±1.70, p<0.0001 and affected HVO hemiarteries: 3.84u±2.14 p<0.0005; unaffected HVO hemiarteries: 4.36u±2.83, p<0.005) compared to normal eyes (5.25u±2.97). In addition, the rate of pulse amplitude reduction along the veins (attenuation) was significantly reduced in all groups compared to normal (-0.08 vs -0.44 log u/mm, p<0.0001). The same trend was observed in the arteries (-0.31 log u/mm vs -0.84 units/mm, p<0.0001).
Conclusions :
Arterial and venous mean amplitudes were decreased in vessels with CRVO and HVO. Amplitude attenuation is reduced in CRVO and HVO subjects compared to normal subjects. Interestingly, the unaffected HVO hemiveins and hemiarteries also had reduced amplitudes and attenuation. Retinal PPG may be useful in predicting and monitoring retinal venous occlusion.
This is a 2020 ARVO Annual Meeting abstract.