Motion detection threshold and field progression in normal tension glaucoma.

Psychophysical tests may demonstrate abnormalities of visual function before the appearance of conventional visual field loss in glaucoma. Motion detection thresholds (MDT) were measured in the normal fellow eye of 51 patients with confirmed normal tension glaucoma and initially unilateral field loss. Humphrey visual fields from the initially normal eye covering a mean follow up of 3.4 years were assessed using pointwise linear regression analysis. In 22 of the 51 eyes with normal visual fields at presentation, field deterioration occurred at one or more Humphrey locations within a mean of 1.7 (SD 1.6) years. An initially abnormal MDT test showed a sensitivity of 73% and a specificity of 90% in predicting field deterioration within the cluster of four Humphrey locations closest to the original MDT test site. Sensitivity was lower (40%) in predicting progression at retinal locations distant from the MDT test site, though specificity remained high (90%).