Objective Quantification of Spontaneous Retinal Venous Pulsations Using a Novel Tablet-Based Ophthalmoscope

Abstract

Dynamic assessment of retinal vascular characteristics can aid in identifying glaucoma-specific biomarkers. More specifically, a loss of spontaneous retinal venous pulsations (SVPs) has been reported in glaucoma, but a lack of readily available tools has limited the ability to explore the full potential of SVP analysis in glaucoma assessment. Advancements in smart technology have paved the way for the development of portable, noninvasive, and inexpensive imaging modalities. By combining off-theshelf optical elements and smart devices, the current study aims to determine whether SVPs can be detected and quantified using a novel tablet-based ophthalmoscope in glaucoma and glaucoma suspects. Methods: Thirty patients, including 21 with confirmed glaucoma (9 men; average age 75 ± 8 years) and 9 glaucoma suspects (5 men; average age 64 ± 9 years), were studied. All patients had intraocular pressure measurements, Humphrey visual field assessment, optical coherence tomography, and a 10-second videoscopy of the retinal circulation. The retinal vasculature recordings (46°field of view at 30 frames per second) were analyzed to extract SVP amplitudes. Results: SVPs were detected and quantified in 100% of patients with glaucoma and those with suspected glaucoma using the novel device. The average SVP amplitudes in glaucoma and glaucoma suspects were 42.6% ± 10.7% and 34% ± 6.7%, respectively. Conclusions: Our results suggest that a novel tablet-based ophthalmoscope can aid in documenting and objectively quantifying SVPs in all patients. Translational Relevance: Outcomes of this study provide an innovative, portable, noninvasive, and inexpensive solution for objective assessment of SVPs, which may have clinical relevance in glaucoma screening.

Heart rate and age modulate retinal pulsatile patterns

“…Previous studies showed that SVP were influenced by the IOP 28 , 35 , 37 , 47 and RNFL significantly correlated with RPP morphological measurements in the dataset, including population with retinal neurodegenerative disesase 4 , 19 , 43 . In our participants, the IOP and RNFL did not correlate with RPP morphology.…”

“…Therefore, the unverified biological impact of HR and age at RPP morphology was in vivo confirmed and validated. The impact of HR and age on the SVP/OCP morphology has been neglected in previous clinical research 4 , 19 , 33 , 34 , 43 and even in theoretical SVP-intracranial/intraocular pressure models 35 , 36 . The in vivo findings validate Levine and Bebie’s theory, assuming that SVP Ampl is influenced by HR 37 , 38 .…”

“…It is important to note that the impact of HR has usually been omitted in previous clinical studies. In particular, ICP studies 33 , 34 (using Hedges scale 48 ) or glaucoma diagnostic studies 4 , 19 demonstrated qualitative or quantitative alterations in RPP morphology without considering group-specific HR distributions. Future studies may avoid potentially blurred and inaccurate outcomes by reporting or, ideally, accounting for the between-group differences in HR.…”

“…Blood flow 14 , 15 , blood volume 4 , 16 and structural venous diameter changes 17 – 19 are the most commonly evaluated hemodynamic parameters from dynamic retinal imaging. The hemodynamic parameters are usually extracted in a manual or semi-automated fashion from specific morphological segments of a retinal vessel tree 16 – 18 , 20 – 23 .…”

“…Exactly how the in vivo video-ophthalmoscopic data (sensitive to blood flow or volume fluctuations) are affected by HR, age, or sex remains to be determined. If the impact of any variable is proved, a revisiting of clinical video-ophthalmoscopic outcomes demonstrating correlations between VO measurements and retinal neural fiber layer (RNFL) thickness 4 , 19 , 43 or other outcomes in populations of healthy subjects and those with disease conditions such as glaucoma is warranted.…”