Distinguishing Familial from Acquired Traits in the Retinal Blood Vessel Arborization

It has been suggested that retinal blood vessel arborization (RBVA) is unique to each individual. We examined this claim in a pedigree that included two pairs of monozygotic twins.

Fundus photographs were taken of subjects belonging to this pedigree to compare the pattern of their RBVA. Pattern prevalence within the general population was estimated from a pre-existing clinical database.

The optic nerve head (ONH) RBVA disclosed the following patterns: pattern A, outgrowth, with angle sizes ranging from 12° to 86°, toward the macula, made by the central retinal (CR) vein; pattern O, circular shape delimited by the CR artery on the nasal side and CR vein on the temporal (macula) side; and pattern Y, a double-Y shape (upright in the superior retina and upside down in the inferior retina) made by the four branches-inferior temporal and nasal and superior temporal and nasal-of the CR artery. The prevalence of patterns A, O, and Y was estimated at 11%, 2.8%, and 2.7%, respectively, from our pre-existing clinical database. Pattern A was the most frequently noted in our pedigree, with a prevalence of 26% to 29%, a value significantly larger (P < 0.05) than that measured in our sample of the general population. Of note, familial similarity is progressively lost as we move away from the ONH.

Relatives appear to share similar ONH RBVA patterns, suggesting that the ONH RBVA could be genetically transmitted as a familial trait. Arrangement of the more peripheral retinal blood vessels would create individuality.

Our results suggest the existence of a specific, reproducible, and transmissible retinal identifier, a feature that could potentially be associated with the prevalence of a given disease process, thus offering the possibility of identifying an underlying retinopathy long before its clinical manifestation and consequently optimize its management.