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Retinal Hemodynamics in Patients with Age–Related Macular Degeneration

Schepens Retina Associates Foundation, Boston, MA

Commercial Relationships: E. Sato, None; G.T. Feke, None; J.W. McMeel, None.

Grant Identification: none

Abstract

Purpose: To investigate whether there is an association between the magnitude of retinal hemodynamic abnormalities in patients with age–related macular degeneration (AMD) and the degree of severity of the AMD.

Methods: A retinal laser Doppler system (Canon Laser Blood Flowmeter, model CLBF 100, Canon Inc, Tokyo, Japan) was used to measure arterial diameter (D), the time variation of the blood velocity (V) during cardiac cycles, the mean velocity (VM) and the blood flow rate (F) in the major temporal retinal arteries in 25 eyes of 25 patients with AMD (16 males, 9 females, ages 62 to 92 years, mean 77 years) and 8 eyes of 8 healthy subjects (3 males, 5 females, ages 64 to 79 years, mean 70 years). Additional hemodynamic parameters determined were the peak systolic velocity (PSV), the end diastolic velocity (EDV), the pulsatility ratio [PR=PSV/EDV], the pulsatility index [PI=(PSV–EDV)/MV], and the resistivity index [RI=(PSV–EDV)/PSV], also known as Pourcelot’s ratio. Severity of AMD was classified according to the method of Mackenzie et al (Ophthalmology, 2002) into Mild (n=11), Moderate (n=7) and Severe (n=7). Visual acuity ranged from 20/15 to 20/200 in the AMD patients, and from 20/15 to 20/40 in the healthy controls.

Results: All three indices of pulsatility (PR, PI, and RI) increased monotonically from the Control Group [PR=4.1±1.1] to the Mild Group [PR=6.4±2.7] to the Moderate Group [PR= 7.8±3.8] to the Severe Group [PR=9.5±5.1]. ANOVA was statistically significant for PR (p=0.027), PI (p=0.005), and RI (p=0.010). The increases in pulsatility were associated with monotonic decreases in EDV across the four groups (p=0.005, ANOVA). EDV ranged downward from 17.6±8.5 mm/s in the Control Group to 7.9±3.1 mm/s in the Severe Group. However, there were no differences in VM, D, or F across the four groups. This suggests that the abnormally increased blood flow pulsatility in the retinal arteries of the eyes with AMD is not due to increased distal vascular resistance, but rather is likely due to an abnormally underdamped blood pressure waveform at the entrance to the retinal circulation.

Conclusions: Our results indicate that an increasing vascular rigidity in the systemic arterial circulation is directly associated with an increasing severity of AMD in the eyes of our patients.

Keywords: age–related macular degeneration • clinical (human) or epidemiologic studies: risk factor assessment • blood supply

© 2004, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved. For permission to reproduce any part of this abstract, contact the ARVO Office at arvo{at}arvo.org.