Performance of nonlinear visual units in ocular hypertension and glaucoma

1. Two psychophysical tests to assess retinal function in ocular hypertension and glaucoma are described. The basis for these tests is the frequency-doubled percept seen with rapid temporal modulation of the contrast of very low spatial frequencies. 2. The results of the second set of experiments show correlation (P < 0.01) with optic disc cupping. Without the inclusion of information about subjects' optic disc condition the second experimental procedure distinguishes the test group from normals (P < 0.01). 3. A model which considers optic disc condition in conjunction with the results of the main experimental method described leads to a separability of normals and a subgroup with moderate disc cupping at the P < 0.001 level. 4. The results reported here, taken together with the current data on retinal ganglion cell function, indicate that harnessing unique features of the frequency-doubled illusion may allow the design of a highly specific and sensitive test for the assessment of early glaucomatous damage.