Retinal haemodynamics in patients with age-related macular degeneration

Objective To investigate whether there is an association between the magnitude of retinal haemodynamic abnormalities in patients with age-related macular degeneration (AMD) and the degree of severity of the AMD. Methods A retinal laser Doppler system (Canon CLBF 100) was used to measure retinal arterial haemodynamic parameters in 25 eyes of 25 patients with AMD and nine eyes of nine age-matched control subjects. Severity of AMD was classified into Mild (n = 11), Moderate (n = 7), or Severe (n = 7). The pulsatility ratio (PR), the pulsatility index (PI), and the resistivity index (RI) were determined. Results PR, PI, and RI in the patients with AMD were each significantly higher than in the control group, and increased monotonically with increasing severity of AMD. However, there were no differences in mean blood velocity, arterial diameter, or blood flow rate among the groups. This suggests that the increased blood flow pulsatility in the retinal arteries of the eyes with AMD is not due to increased distal vascular resistance, but instead is likely due to a loss of compliance in the arterial vasculature leading to the eye. Conclusion Our results suggest that an increasing vascular rigidity in the systemic arterial circulation is directly associated with an increasing severity of AMD.