Clinical measures of central differential sensitivity in glaucoma

To verify whether central threshold testing with a common automated perimeter could detect glaucomatous damage, we selected 40 eyes with primary open-angle glaucoma and 43 eyes of age-matched normal subjects. The glaucomatous eyes were free from visual field defects within the central 5 degrees. They underwent the Macula Threshold Test of the Humphrey perimeter, using white and blue targets. Differential sensitivities to both white and blue were significantly depressed in the glaucoma group (p less than 0.001). Blue thresholds of glaucomatous subjects and normal subjects were distributed in two quite separate domains, with a mean difference of 4.51 dB. Sensitivities to blue stimuli were related to age in the normal group (r = 0.62; p less than 0.001), while in the glaucoma group they were related to horizontal cup/disc ratios (r = 0.63; p less than 0.001). These results suggest that threshold testing with an automated perimeter and its built-in colour filters can be of help in detecting early central functional disturbances from glaucoma.