Studies on retinal blood flow. I. Estimation of human retinal blood flow by slit-lamp fluorophotometry

J. G. Cunha-Vaz and J. J. Lima

This article describes a new direct method for estimation of human retinal blood flow by slit-lamp fluorophotometry. The apparatus consists fundamentally of a modified slit lamp with an eye piece containing two fiberoptic probes connected to a double photometric detection system. Both optic fibers are focused on a retinal arterial segment, and the passage of a fluorescein bolus is automatically registered, giving, after correction, the mean transit time. Fluorescein angiography allows the determination of the volume of the arterial segment under study. Values for superior temporal retinal blood flow in healthy individuals show a mean value of 4.2 +/- 0.5 microliter/min. Studies in anemic patients show an increase of approximately 52% in the retinal blood flow. The potential causes of error associated with this technique, apart from the slight increase in intraocular pressure induced by the contact lens used, do not appear to be significant.