Is there general reduction of sensitivity in glaucoma?

Ten normal controls, ten ocular hypertensive patients, ten high tension, 12 medium tension and nine low tension glaucoma patients were studied prospectively by means of automated static perimetry. Multiple double threshold measurements were obtained during at most three years. A computer algorithm estimated for each visual field the Individual General Sensitivity IGS, in which local defects do not contribute. Thus we were able to estimate pure general reduction of sensitivity by comparing the IGS to age-corrected normal reference values. No significant difference in mean general reduction of sensitivity was found between the glaucoma patients and the normal group. Patients with local defects in one field half only also showed IGS values not different from normals. Our findings indicate that the impression of 'general' sensitivity loss may be caused by the presence of multiple local defects, and is not a phenomenon in itself.