Abstract
Purpose :
Doppler holography offers a novel method for quantitatively estimating hemodynamics in the primary in-plane retinal arteries over the cardiac cycle. This technique is aimed at diagnosing and monitoring ocular vascular disorders. An assessment of blood volume rate variations is done in a glaucoma patient and a patient with Central Retinal Vein Occlusion (CRVO).
Methods :
High-speed digital holography with near-infrared laser was used to image patients with 67 kHz framerate camera. Doppler image rendering reveals blood flow contrasts in the eye fundus. The local blood flow velocity was estimated in segmented retinal arteries by measuring the differential in local Doppler broadening of light passing through retinal vessels compared to their surrounding area. A forward scattering model of dynamically diffused light was used to derive blood flow velocity that scales up linearly with the local broadening frequency difference. The local blood volume rate was assessed by multiplying the velocity by the cross section of the artery. The total arterial blood volume rate was determined by summing of each local arterial volume rate emerging from the Central Retinal Artery. This approach enabled a parameterless estimation of local blood volume rate in retinal arteries throughout the cardiac cycle.
Results :
A 60-year-old man with an open angle glaucoma needed a needling after surgery and showed a decrease of intraocular pressure (IOP) from 38 mmHg to 7 mmHg between the two Doppler measurements performed just before and after the procedure. A 45 year-old woman with CRVO in her left eye underwent an initial Doppler measurement. Her condition evolved towards the development and the majoration of collateral venous shunts after 27 days, when the second Doppler measurement was done. Both cases exhibited a substantial increase in total arterial blood volume rate following treatment: for glaucoma, from 11.9±3.0µL/min to 20.2±3.5 µL/min, and for CRVO, from 13.4±4.8µL/min to 30.2±4.7 µL/min.
Conclusions :
The quantitative assessment of retinal blood volume rate through Doppler holography in both glaucoma and CRVO cases indicates its promising utility in monitoring vascular alterations.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.