A forced choice procedure for evaluation of contrast sensitivity function in preschool children

The ability to clinically use Contrast Sensitivity Function (CSF) in adults for detection of visual pathway disorders has been demonstrated. The results of CAF testing would be especially meaningful clinically for young children for earlier diagnosis and treatment of visual disorders. In preschool children (ages 3-5 years), CSF assessment has been more laborious and less practical clinically and has met with limited use or success when dealing with preschool children. The purpose of this study was to evaluate the effectiveness of a modified two-alternative forced choice (2AFC) procedure in testing the CSF in preschool children.

The subjects in this study consisted of 26 children between the ages of 35 and 60 months of age. The children were free of any detectable visual deficits, illness, and neurological or developmental abnormalities. A Vistech Vision Contrast Sensitivity System (CTS 6500) chart was modified and applied in a two-alternative forced choice procedure to determine the contrast sensitivity threshold for five spatial frequencies (1.5, 3.0, 6.0, 12.0, and 18.0 cycles/degree).

All 26 children completed the testing at all five spatial frequency levels with both eyes under monocular testing conditions. The average actual testing time required less than 7.0 minutes for the combined right and left eye test time for all subjects. The results suggest that as the age increased, there was a tendency for an overall increase in the child's ability to detect lower contrast levels. The results indicate that this modified procedure yielded values proximal to adult CSF values, especially in the higher spatial frequencies.

We have demonstrated that a modified forced-choice procedure using Vistech CSF gratings could be used in a preschool population. The two alternative forced choice method used in this study was found to be an effective and clinically efficient technique for evaluating the CSF levels in preschool children and makes it possible to screen for a variety of visual and neurological conditions in the preschool child.