Abstract
Purpose: :
Doppler spectral-domain 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 retinal blood flow (RBF) measurements obtained using Doppler OCT.
Methods: :
One eye of each human subject was scanned with the Optovue RTVue spectral-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: :
Two males and six females with average age of 56.9 ± 9.02 years were included in the study. Of the 8 eyes, 1 was normal, 3 had perimetric glaucoma, and 4 had suspected glaucoma or pre-perimetric glaucoma. Total retinal blood flow showed a trend to be slightly higher following dilation (mean 34.7 µl/min) compared to before dilation (31.1 µl/min) (p=0.08). Total retinal vein area and average venous velocity showed a small but non-significant increase after dilation, from 0.040 to 0.041 mm2 (p=0.28), and 13.1 to 14.6 mm/sec (p=0.18), respectively.
Conclusions: :
Mydriasis using conventional topical agents appears to have minimal effect on Doppler OCT - derived posterior retinal blood flow measurements. Although there was a trend for a small increase in retinal blood flow, the differences may not be clinically meaningful. This information should be of value in the design of future Doppler OCT studies. Further clinical studies are necessary to determine whether there may be differences in mydriasis-induced effects on retinal blood flow among normal patients, patients with perimetric glaucoma, pre-perimetric glaucoma, or other disease etiologies.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • blood supply • imaging/image analysis: clinical