Abstract
Purpose::
We have developed a new CSF system -called VISTUC - that includes two standards by age group (20-49 and 50-69 years old). In this work we asses the sensitivity of this system when it is used as a screening tool in a non clinical population.
Methods::
The VISTUC is a CSF system specially designed for a clinical environment. The equipment is based on a standard PC and allows generating sinusoidal gratings of any orientation with spatial frequencies ranging from less than 1 c/deg up to values around 25 c/deg. The contrast ranges from 0.002 to 1 with errors varying between 1.5% and 10%. The two normal ranges were obtained with 103 eyes of subjects who passed a full eye examination and, if necessary, were refracted in situ to the test distance. Here we report measurements of 79 eyes (range 20-49: 56 eyes; range 50-70: 23 eyes). Subjects were visitors of a Science Exhibition and performed the test in a noised and visual polluted environment. The subjects perform an orientation discrimination experiment with an adaptive 2AFC procedure to determine the contrast thresholds. They were adapted to the mean luminance of the screen (70 cd/m2) and were kept to a distance of 1,5m from the stimulus. A training trial was done before the FSC measurement. Spatial frequencies of 1, 4 and 12 c/deg were measured.
Results::
From the total of the checked eyes 32% differed from the ranges of normality. In the 20-49 years old group, refractive errors or cataracts could explain 21% and 9% needs a full examination in order to determine the cause of their visual losses. In the 50-69 years old group these values were 17% and 17%, respectively.
Conclusions::
These results suggest that this CSF vision test can provide useful information when is used as a screening tool in complex environments.
Keywords: contrast sensitivity • aging: visual performance