Automatic perimetry in detecting early glaucomatous visual field defects. A follow-up study.

A prospective study was conducted to identify the value of the differential light threshold changes in glaucoma patients. Using Humphrey Field Analyzer, we determined the differential light threshold on 42 preselected points in the Bjerrum area in the age-matched early glaucoma and normal group, each in 50 eyes, whose initial Goldmann perimetries were normal. It was found that both generalized and localized sensitivity of the retina declined obviously in the glaucomatous group. After Goldmann perimetry follow-up for 2.5 years, 24 eyes showed reproducible typical visual field defects (VFD) in the glaucoma group, which appeared in the same location where light threshold had reduced previously. Therefore, a typical glaucoma VFD was preceded by the slight localized depression of light sensitivity in the Bjerrum area.