Contrast sensitivity in a large adult population.

The contrast sensitivity test (using Vistech charts) was performed on a consecutive sample of 1612 eyes of 807 Republic of Singapore Air Force personnel (two diseased eyes excluded), which had no known ophthalmic disorder. This yielded a large sample norm of spatial Contrast Sensitivity Function (CSF) distribution curves, based on the local population. Although all subjects had their refractive errors fully corrected by spectacles, whenever necessary, to visual acuity of 6/6 or better, myopes had lower mean contrast sensitivity, in the higher spatial frequencies, compared to the emmetropic. Postulates were offered to explain this association, including the concept of micro-amblyopia. Pilots and aircrew performed consistently better than the ground crew, suggesting that target acquisition training may improve contrast sensitivity. Interestingly, sex was also shown to be associated with differences in contrast sensitivity: females were found to have lower spatial contrast sensitivity compared to males. Age was associated with poorer contrast sensitivity only at the lower spatial frequencies in this study sample, while race, with that of higher frequencies; Chinese having lower contrast sensitivity than other races (a heterogeneous group consisting of Malays, Indians, Eurasians and Others). The association of contrast sensitivity with race highlights the importance of using normograms based on the local population. All the above associations were statistically significant at P = 0.05, and independent of each other, based on analysis by multiple regression.(ABSTRACT TRUNCATED AT 250 WORDS)