Disorders of the anterior visual pathways

Persistent photopsia are a feature of retinal disease, either degenerative, inflammatory (for example, acute zonal occult outer retinopathy (AZOOR) that characteristically presents acutely with unilateral visual field loss, photopsia, and normal fundal examination but abnormal electroretinograms (ERGs)), or paraneoplastic (cancer or melanoma associated retinopathy). A relative afferent pupillary defect (RAPD) caused by retinal disease requires extensive asymmetric disease with macular involvement-for example, subtotal retinal detachment. [...]in most cases there will be obvious fundal changes but retinal disease may not be apparent on fundoscopy.