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N. Nguyen, G. Wu, D. A. Lee, B. Tate, R. Garcia, J. Lee, G. J. Tso, Q. Nguyen, P. N. Nguyen; Measurement of Flow in Retinal Vascular Disease Using Digital Fluorescein Angiography. Invest. Ophthalmol. Vis. Sci. 2008;49(13):611. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
We propose a mechanism of measuring blood flow using fluorescein angiography.
The equation: Flow=(πr2L)/t (mm3/sec):r=radius of blood vessel, L=length of blood vessel, L= 1000µ, using the splining algorithm of the Topcon camera 50EX system, OIS Winstation-XP 3200 v. 10.2.44. Digital fluorescein angiography (FA) was performed using Sodium Fluorescein 10%. The patient's vein diameter was measured at the 12:00 position of the optic nerve, at the height of venous hyperfluorescence of the digital FA. Time was defined as the difference between the initial hyperfluorescence of the cilioretinal artery, t initial, and the first appearance of a fully hyperfluorescent vein as t final. Visual acuity for the study patients was 20/20 -20/40. We examined digital FA of patients with minimal retinal disease, Controls (C) and patients with previously diagnosed Retinal Vascular Disease (VASC). C diagnoses were central serous choroidopathy, glaucoma suspect, retinal holes. VASC diagnoses were branch retinal vein occlusion, central retinal vein occlusion, diabetic retinopathy and ocular ischemia.
18 pts:9C, 9 VASC: C age range= 24-77 yrs, avg= 48.75 yrs +15.9, VASC age range=32-72 yrs, avg=53.75 yrs +14.33( p=ns). Vein diameter: C=146.44µ + 14.04, VASC=143.33µ +11.24 (p=ns). Using the Flow equation: C pts: avg Flow =1742.7 mm3/sec + 605.51; VASC pts: avg Flow=1255.27 mm3/sec +329.99. The C pts had faster flow than those of the VASC pts (p<0.05, t-test).
The findings suggest an approximation of flow can be performed using standard fluorescein camera equipment and software, found in the offices of retinal specialists. In this small study, Retinal Vascular Disease patients had a slower flow rate than those of the Control patients. In the future, this flow measurement may be useful in the evaluation and management of retinal vascular disease.
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