A comparison between different contrast sensitivity tests in the detection of amblyopia

Twenty adult patients with strabismic amblyopia were examined with seven different contrast sensitivity tests in order to determine which of these tests is the most sensitive in the detection of amblyopia. Both grating tests (Vistech, Arden, Cadwell, and Cambridge) and optotype tests (LH, Regan, and Pelli-Robson) were used. The following parameters of the contrast sensitivity function (CSF) were measured: maximum contrast sensitivity, total area of CSF and the area of 8 different spatial frequency bands in the CSF. Based on non-parametric tests, it was found that separations of the normal from the amblyopic eye by means of CSF could be done with: - maximum contrast sensitivity using the Vistech test; - total CSF area using all tests except the Cadwell test; - area of frequency bands (within 1-16 cycles per degree) using Vistech, Pelli-Robson, and the Arden tests; - maximum spatial frequency for tests with a fixed contrast using the LH and Regan tests.