Abstract
Purpose: :
To investigate human retinal blood flow changes in response to visual stimulation.
Methods: :
A Fourier-domain optical coherence tomography (FD-OCT) system with the speed of 26,000 axial scans per second and axial resolution of 5 µm in tissue was used. The flicker stimulus apparatus consisting of a ring of LED was mounted around the objective lens of the Doppler FD-OCT system. Total retinal blood flow was measured firstly in the absence of light stimulation for each subject. After baseline measurement, the LED light was on for thirty seconds at an ocular exposure less than 1.0 Candela/cm2 (well below the ANSI limit). When the LED light is off, a retinal blood flow measurement was performed immediately. Retinal blood flow at different light brightness was measured, and compared with baseline result. One eye was scanned in each subject.
Results: :
Total retinal blood flow (TRBF) in 2 normal subjects was 42.4 and 41.6 µl/min separately without stimulation light. TRBF increased with the increasing of stimulation light brightness. For the first subject, TRBF had a maximum increase of 16.3%. For the second subject, TRBF had a maximum increase of 35.0%. For both subjects, TRBF showed saturation when stimuli brightness higher than 0.47 Candela/cm2.
Conclusions: :
We present thefirst report of Doppler OCT performed in the measurement of retinal blood flow response to visual stimulation. This Doppler OCT detected an increase in retinal perfusion at light stimulation. The TRBF change showed saturation at high stimuli brightness. Doppler OCT may be useful in the assessment of the activity-induced vascular changes in human retina. Further studies will help clarify the clinical implications.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina • blood supply