[The clinical significance of following up the differential light threshold in glaucoma]

The correlation of the differential light threshold changes in the Bjerrum area to the glaucomatous visual field defects that followed was studied prospectively by the Humphrey Field Analyzer. Of 42 early glaucomatous eyes without field defects, 24 developed reproducible glaucomatous field defects in 2.5 years of follow-up. The agreement in location between the field defects and the meridian of highest light threshold elevation was remarkable (87.0%), and a mean 5 dB decline in local light sensitivity predicted ensuing field defect development. Thus, the discovery of glaucomatous field defects with automated Humphrey perimetry could be 1-2 years earlier than with Goldmann perimetry.