Abstract
A new numerical representation of visual field based on the density of the receptive fields of retinal ganglion cells was applied to evaluate the clinical courses in 30 cases of chiasmal tumors. Preoperatively, on the basis of Goldmann's perimetric projection, the visual field defects were subdivided into four groups: normal, incomplete hemianopia, complete hemianopia, and marked defect. The mean numerical value (visual field volume) of each group was related to the degree of the visual field defect. Postoperatively, the visual field volume improved in 58%, was unchanged in 17%, and worsened in 25%. In terms of the change in visual field volume, there was no significant difference between the transfrontal and transsphenoidal approaches. The degree of visual improvement was correlated with the extent of the preoperative visual field defect. In cases of incomplete hemianopia, surgical removal may restore the visual field to almost normal. However, once complete hemianopia has occurred, vision cannot be completely restored.
