Abstract
Purpose :
Neurovascular coupling (NVC) is the capability of vessels in neural tissue to adapt to neuronal demand. Here we report the results of flicker-induced dilation of retinal arterioles in normal subjects using adaptive optics ophthalmoscopy (AOO).
Methods :
The command program of the internal fixation light of a commercially available flood-illumination adaptive optics camera (rtx1, Imagine Eyes, Orsay, France) was modified to accomodate a 28°x20° flickering yellow light emitting diode, which is the light used for fixation target. The clinical procedure comprises 3 basal images before stimulation (taken within ± 60 seconds), followed by 3 periods of flickering stimulation at 15Hz during 20 seconds each; the image was captured during the last 2 seconds of the stimulation cycle. AOO images of arterial segments of at least 250 µm long in the posterior pole were segmented offline using a custom software (AOV image, developed by Florence Rossant). The protocol was approved by an ethical committee (Comité de Protection des Personnes).
Results :
21 eyes of 21 controls (10 females and 11 males; mean age ±SD 38.4 years ±12.7) were examined. The average diameter of the arteries lumen was 85.1 µm (±20.4). The difference between the basal measurements ranged from -2.22% to +2.86% with an average of +0.17%. Flicker-elicited dilation ranged from +0.83% to +6.63% with an average of +2.98%. The average wall to lumen-ratio of the vessels was of 0.24. Dilation was independent from age and size of vessel, but was inversely correlated with WLR (p<0.05) (Figure 1).
Conclusions :
AOO-based NVC analysis offers a novel approach of the evaluation of the vasomotricity of retinal vessels. The vasodilation was found comparable to that reported using other methods, with the additional advantage of analyzing local changes and the concomitant measurement of the WLR. The latter as found to be inversely correlated to flicker-induced vasodilation. This may be an indication that microvascular tone may influence flicker response.
This is a 2021 ARVO Annual Meeting abstract.