Retinal Vessel Analyzer (RVA)--design and function.

The Retinal Vessel Analyzer (RVA) is a measuring device for online measurement of the diameter of retinal vessels in relation to time and locations along the vessel. It is furthermore provided with several tools for analyzing the measured data. The fundamental components consist of a fundus camera with CCD measuring camera attached and an advanced image-processing unit. The measurement range is from 90 microns, temporal resolution is 40 ms and measurement resolution is less than 1 micron. Systematic error of non-linearity is S < or = 1.6%, reproducibility is given by variation coefficient: short term vcs = 1.5%, long term vcl = 2.8%.