Correlation of relative afferent pupillary defect and estimated retinal ganglion cell loss

Abstract

Background: The relative afferent pupillary defect (RAPD) is an important parameter for quantifying the loss of neuronal function in asymmetric optic nerve disease. We wanted to assess its correlation with retinal ganglion cell loss, estimated from visual field defects, using a recently described method. Methods: In 36 patients with unilateral optic nerve disease, the RAPD was measured using an automated, computerized infrared pupillometer. The percentage of ganglion cell loss was estimated with clear templates. Results: We found a highly significant correlation between the RAPD and estimated ganglion cell loss. The correlation was higher for Humphrey visual fields than for Goldmann visual fields measured with the I4e and I2e stimulus. Conclusion: The RAPD correlates well with estimated retinal ganglion cell loss in optic nerve disease. Humphrey visual fields seem to reflect the ganglion cell loss better than Goldmann visual fields. The spatial distribution of pupillomotor retinal ganglion cells seems to be proportional to the distribution of light-sensitive ganglion cells projecting to the lateral geniculate nucleus.