Assessment of Spatial and Temporal Modulation Transfer Functions in Early Glaucoma by Means of the Pattern Visual Evoked Potential

Abstract

It has generally been believed that the central visual function of patients with primary open-angle glaucoma (POAG) is not affected until quite late in the disease. However, Quigley et al. (1982) have demonstrated by clinical and histopathological studies that up to 50% of retinal nerve fibers may be lost before either Goldmann perimetry or Snellen measurements can detect any abnormality. Their studies also demonstrated that nerve fibers are lost everywhere in the retina as glaucoma progresses, although the loss is greater at the superior and inferior poles of the optic disc. If we postulate that optic nerve fibers including those at the macula are diffusely impaired at an early stage of glaucoma, then disturbance of central visual function may be found by more sensitive tests for visual damage.