Walsh & Hoyt: Photo Stress Test

The differentiation between unilateral retinal disease and retrobulbar optic neuropathy may be aided using the photo stress recovery test described by Glaser et al. This test is based on the principle that visual pigments bleach when exposed to an intense light source, resulting in a transient state of sensitivity loss and reduced central visual acuity. Recovery of retinal sensitivity is dependent upon regeneration of visual pigments, which is determined by the anatomic and physiologic apposition of the photoreceptors and retinal pigment epithelium. It is independent of neural mechanisms. Diseases that produce visual loss by damaging the photoreceptors or the adjacent retinal pigment epithelium cause a lag in regeneration of pigment, resulting in a delay in visual recovery following light stress.