Reference values of optical coherence tomography angiography metrics vary
according to the device used to measure them and even based on the software on the
same device. There might exist measurement differences between different maps
within the same device: Variables such as age, gender, and signal strength might induce
changes in the measurement outputs.
This chapter deals with the values of vessel length and vessel area densities, and foveal
avascular zone values of healthy emmetropic people via the 3 × 3 mm map used in the
most common equipment that are available commercially. The text includes metrics of
the parafovea and fovea at the superficial, intermediate, and deep capillary plexuses.
These measurements corresponded to the adult non-diabetic population and were
distributed as center (foveal), inner (parafoveal) and full (whole map) densities,
depending on the evaluated region, according to densities in the foveal, parafoveal, and
whole map measurements. Metrics of the parafovea by subfield were also included. We
also report current cut-off values that have been proposed as normality references in
some variables. Values for the remaining metrics and devices can later be proposed.
We dedicate a special section to non-diabetic patients with high myopia without
pathology, which includes the same metrics as in emmetropic patients. The evaluation
of perfusion indices benefits from the simultaneous measurement of metrics as well as
regional evaluation. The signal strength is a key variable to consider.
Keywords: Area, Deep capillary plexus, Emmetropia, Foveal avascular zone, Middle capillary plexus, Myopia, Perimeter, Superficial capillary plexus, Vessel area density, Vessel length density.
