| Glaucoma is a disease that is difficult to diagnose in its earliest stages. With the aging of the U.S. populations, it is likely that the incidence and prevalence of glaucoma will increase, making its early diagnosis more critical than ever. Previous research suggests that glaucoma causes changes in photoreceptors and ganglion cells that might be detectable using psychophysical techniques that are sensitive to small anatomical or functional changes in the retina. The research developed a new approach to psychophysical testing that may enable glaucoma to be diagnosed earlier than present techniques allow. This new approach was used to measure the foveal sensitivities in subjects with and without primary open angle glaucoma. Foveal sensitivities were measured in the horizontal meridian both nasally and temporally from the foveal center in increments of 0.26 degrees while the subjects' eye position was monitored. The stimulus was a 13' (minute) flash in the center of a 6 degree adapting background field. At each foveal test position, the stimulus was presented four times, and the results were averaged. Analysis showed a 0.4 log unit overall difference in foveal sensitivity between the normal subjects and those diagnosed with glaucoma. Foveal sensitivity was attenuated in the subjects with primary open angle glaucoma. These results suggest that this test may be useful for the early diagnosis of glaucoma. |
