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D. Nelson, Z. Burgansky-Eliash, R. Silva, O. Pupko, A. Grinvald; Comparing Retinal Blood-Flow Velocity Between Dry and Exudative Age Related Macular Degeneration by the Retinal Function Imager. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3441. doi: https://doi.org/.
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The Retinal Function Imager (RFI) is a non-invasive imaging system that provides quantitative information about blood flow (BF) velocity in the retina. In this study we compared blood flow velocity in the retinal vasculature between dry age related macular degeneration (AMD) and exudative AMD.
28 eyes of 14 patients with AMD were enrolled in this study. All patients had exudative AMD in one eye and dry AMD in the fellow eye. All patients underwent RFI examination in both eyes. Blood flow velocities were compared using Student's t-test. Vessel segments were categorized into 3 size groups: 'small' if smaller than 10µm, 'medium' if between 10-20µm and 'large' if larger than 20µm.
In dry AMD eyes, the mean overall velocity in veins was 2.8 ± 0.5 mm/sec; significantly faster than for veins in exudative AMD eyes (2.2 ± 0.8 mm/sec, p=0.04). Slower flow velocity was also noted in exudative AMD eye compared to the dry AMD one when comparing veins in each size category (2. 4 ± 0.2 vs 1.4 ± 0.4 mm/sec, p=0.03 in small veins, 2.5 ± 0.4 vs 1.9 ± 0.7 mm/sec p=0.04 in medium veins, 3.2 ± 0.6 vs 2.3 ± 0.8 mm/sec p=0.009 in the large veins). In retinal arteries, only small arteries showed significantly slower velocity in the exudative AMD eye compared to the wet AMD eye (3.16 ± 0.5 vs 2.1 ± 0.9 mm/sec p=0.03). In larger arteries there was no significant difference in velocity between the eyes.
Reduced blood flow velocity in the exudative AMD eye compared to the dry AMD eye could be a result of regionally decreased flow as a secondary autoregulation response to AMD damage. Another alternative is that this finding is a result of a more general perfusion abnormality, with common degenerative changes in connective tissue causing both vascular abnormality and AMD.
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