The fundus vessels of 50 institutionalized mongols were compared with the fundus vessels of 50 sex-matched controls of similar age. Mongols appear to have significantly more retinal vessels crossing the margin of the optic nerve head. The high number of vessels is associated with an unusual, spoke-like appearance of the retinal vasculature and may be helpful in the clinical diagnosis of Down's syndrome (mongolism) in the newborn.
Williams EJ, McCormick AQ, Tischler B. Retinal Vessels in Down's Syndrome. Arch Ophthalmol. 1973;89(4):269-271. doi:10.1001/archopht.1973.01000040271001