Quantification of congruence between the right and left visual fields.

In the past, congruence between the right and left visual fields could only be evaluated subjectively. This study presents a congruence index to assess the similarity of the two visual fields objectively and quantitatively based on probability calculations. In 18 patients with suprachiasmal lesions of the visual pathways (cerebrovascular accident or tumor), the index found a homonymous congruence in all cases (100%). Of 26 persons with pituitary adenoma, in 22 cases (85%) the index found heteronymous congruence. The validity of the method may be even higher, because all cases with atypical indices also had atypical congruence by subjective evaluation. Using this new method in 41 patients with primary open-angle glaucoma, heteronymous congruence was detected in 73% and homonymous congruence was found in 17%. This new index may be useful for the development of computerized parametric methods of differential diagnosis.