Abstract
Purpose :
Investigate the relationship between hypointense bands in optical coherence tomography angiography, real-time angiography (fluorescein and indocyanine green), and ophthalmodynamometry, describing a noninvasive marker of slow retinal blood flow.
Methods :
A case series of: healthy subjects; patients with clinical diagnosis of retinal vascular occlusion and patients with occlusive carotid disease. Swept-source OCT-Angiography (SS-OCTA, PlexElite, Carl-Zeiss, Germany) was performed using different scanning directions and speeds. Additionally, on group a) a Bailliart dynamometer was used to induce a raise of the IOP, until pulsatile flow was visible in ophthalmoscopy, suggesting the IOP had dropped the mean ocular perfusion pressure to between systolic and diastolic blood pressure. SS-OCTA scans were segmented to obtain en-face images of the superficial vascular plexus (SVP), deep capillary plexus (DCP), and choriocapillaris (CC).
Results :
On groups b) and c), spontaneous hypointense bands of similar height were seen horizontally in square scans, and vertically in rectangular scans. Those bands were thinner and more numerous at 100 kHz compared to 200 kHz speed scan. Dark bands were correlated slowed and pulsatile flow in real-time angiography. The same pattern was detected in group a) after increasing IOP with a dynamometer. In addition, in patients with acute RVO, the pattern was seen exclusively in the en face panels showing flow in the inner retinal layers, whereas in patients with iatrogenic high IOP, the hypointense bands were also detected in the CC.
Conclusions :
SS-OCTA hypointense bands are a non-invasive marker that represents slow retinal flow and are associated with pulsatile flow in real-time angiography. These bands are not detectable until there is a significant reduction in MOPP, either because of increased IOP, acute RVO or carotid artery stenosis. Detecting flow speed below SS-OCTA threshold might be useful for spotting vascular occlusive disease in clinical practice.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.