Measurement of flicker induced hyperemia in the retina and optic nerve head by Laser Speckle Flowgraphy

Abstract

Purpose : Ocular blood flow regulation during stimulation with flicker light has been extensively investigated using a variety of different techniques. The aim of the present study was to evaluate whether Laser speckle flowgraphy (LSFG), a new commercially available technique for measuring ocular blood flow, is capable to assess flicker-induced hyperemia in the retina and optic nerve head (ONH).

Methods : Twenty healthy subjects (mean age 25±7 years) participated in this cross-sectional study. Retinal and ONH blood flow was measured before and during stimulation with flicker light. Mean blur rate (MBR) in the ONH (MBR_ONH) and relative flow volume (RFV) in retinal arteries (RFV_ART) and veins (RFV_VEIN) were assessed using LSFG.

Results : Stimulation with flicker light induced a significant increase in MBR_ONH by +17.5%±6.6% (p<0.01), as well as in RFV_ART by +23.8±10.0% (p<0.05) and in RFV_VEIN +23.1%±11.0 (p<0.05). When comparing retinal sectors, the observed response was higher in nasal RFV compared to temporal RFV in arteries (nasal: +28.9%±20.0%; temporal: +20.4%±17.6%, p<0.05) and also in veins (nasal: +28.3%±19.6%; temporal +17.8%±18.9%, p<0.05).

Conclusions : As expected, flicker stimulation led to a significant increase in retinal and ONH blood flow. These results indicate that LSFG is an appropriate method to study flicker-induced hyperemia in the retina and ONH and may be applied as a non-invasive, easy to use tool to assess neurovascular coupling in the future.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.