[Changes in contrast sensitivity in glaucoma patients]

To evaluate changes of temporal contrast sensitivity (TCS) in patients with glaucoma.

We measured TCS (for 10, 20 and 30 Hz frequencies) in 57 eyes with glaucoma using a prototype that produces a red colour flicker stimulus (lambda = 626 nm) projected in the central 320 of the visual field. In all patients measurements were undertaken for the visual acuity and intraocular pressure. Also the optic disc was evaluated (including C/D ratio), as well as the visual field using the 24/2 program of the Humphrey automated perimeter.

For all tested frequencies we computed sensitivity and specificity of the test S < 0 as diagnostic tool for glaucoma. The sets of determination with 30 Hz flicker stimulus have a validity score of 83.8%. We also evaluated the correlation curves between the S score, C/D ratio and mean deviation from automated perimetry.

Patients with glaucoma present a significant drop of the S score for all three tested frequencies. The S score positively correlates with mean deviation (MD) and negatively with C/D ratio reflecting thus diffuse alterations of the magnocellular system. The decrease of the S score in the 30 Hz set of data is major and S < 0 as a diagnostic test has very good sensitivity and specificity. S score might be used in screening for glaucoma as well as monitoring progression of the disease (rapid test, low cost, good validity).