The light reflex in retinal vessels and its relation to age and systemic blood pressure.

The light streak characteristics on retinal vessels were studied by microdensitometry on fundus photographs. We compared the width and the intensity of the reflex in a young group (mean: 19.7-year-old; n = 40) and in an older group (mean: 45.3-years-old; n = 22) of normal subjects. By subgrouping according to age and blood pressure levels, we studied possible effects of these parameters on the light streak. We found higher intensity of reflection from both arteries and veins in the older group (P less than 0.01). This effect seemed mostly related to the age of the subjects. We also registered a relation between systolic blood pressure and intensity of reflection from veins in the young group (P less than 0.03). Optical changes in the vessel walls in the ageing process and intravascular pressure effects on the indices of refraction in the erythrocytes/plasma may account for these findings. The width of the reflex was not found to be related to either the age or the blood pressure level of the subjects.