Leon F. Garner

The effect of a moderate level of hypoxia on human color vision

This study reports the effect of a moderate level of hypoxia on human color discimination. We found a generalized loss of color vision affecting both red-green and blue-yellow discrimination at an altitude of 12,000 feet. Although the residual color discrimination at this altitude was within age-matched, sea-level norms, a statistically significant increase over sea level error scores was measured on the Farnsworth-Munsell 100-Hue test and the Pickford-Nicolson anomaloscope. An analysis of psychophysical and electrophysiological studies indicates that hypoxia acts by depressing retinal ganglion cell activity and that it can affect photopic visual processes as well as scotopic vision. We conclude that studies evaluating mans visual performance at altitude must consider post-receptoral processes.

Vision Problems In Tonga: Report On The University Of Auckland Visit – August 1981

A team from the University of Auckland conducted an assessment of vision needs in Tonga in August 1981. A total of 667 people was examined with a mean age of 50.6 years. The vast majority (91.6%) had no spectacle correction for either distance or near. The onset of presbyopia appeared to occur at an earlier age than in European societies and the majority of spectacle prescriptions ordered (77.4%) were for near work. A high incidence of pterygium (23.2%) was detected by the team.