[Fundus examination of newborns on Tibet plateau]

Fundus examination of 255 newborns in high altitude Tibet revealed that the optic discs were of orange-pink colour with clear margin and over ten small vessels. The C/D ratio in 500 eyes (98.04%) was 0.3 or less, and none was 0.6 or over. The C/D ratio in both eyes of 242 babies (94.90%) was symmetrical and in only 1 case (0.39%) it differed by 0.2. The macula of all infants was dark red with no foveal reflection. Some of the veins were engorged. Retinal hemorrhages were found in 64 cases (25.10%), 12 cases in the macular region and 1 case on the optic disc. Retinal edema was present in 30 cases, cotton wool exudates in 30 cases, vitreous artery in 6 cases, and congenital cataracts in 1 case. The mechanism of retinal changes were discussed.