Abstract
Purpose:
Doppler optical coherence tomography (OCT) with the circumpapillary double-circular scan pattern is a novel method of measuring retinal blood flow. The purpose of this study is to evaluate the effect of mydriasis on total retinal blood flow (TRBF) measurements obtained using Doppler OCT.
Methods:
One eye of each human subject was scanned with the Optovue RTVue Fourier-domain OCT using a double circular Doppler scan pattern centered on the optic disc. The Doppler OCT images were processed by a software algorithm that automatically identifies arteries and veins and computes their positions, diameters, and flows. The Doppler scans were obtained both before and after pupillary dilation using 1% tropicamide and 2.5% phenylephrine. Multiple retinal blood flow parameters were computed, including total flow (µl/min), total venous cross-sectional area (mm2), and average venous velocity (mm/sec). Values were compared before and after dilation.
Results:
Twenty five patients with average age of 57.7 ± 8.88 years were included in the study. Of the 25 eyes, 6 were normal, 8 had perimetric glaucoma, and 11 had suspected glaucoma or pre-perimetric glaucoma. Total retinal blood flow showed was significantly higher following dilation (mean 36.9 μl/min) compared to before dilation (33.9 μl/min) (p=0.02). Total retinal vein area and average venous velocity showed a small but non-significant increase after dilation, from 0.044 to 0.045 mm2 (p=0.07), and 12.9 to 13.9 mm/sec (p=0.07), respectively.
Conclusions:
Mydriasis using conventional topical agents slightly increased TRBF as measured by Doppler OCT. This 8% increase may have a small effect on clinical studies if pupil dilation is not consistently performed. Since dilation tend to improve Doppler signal, we recommend consistent dilation for clinical studies using the current generation of Doppler OCT technology.
Keywords: 549 image processing •
628 optic flow •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)