The aim of this chapter is to focus on the diagnosis of chloroquine retinopathy. Screening strategies for antimalarial retinal toxicity are still controversial, mainly because there is a difficulty in defining the early stages of retinopathy. Additionally, in well-monitored and dosed patients, the incidence of retinopathy is low. It is, therefore, important to first define chloroquine-associated toxicity. Most ophthalmic textbooks divide retinopathy into five stages. This chapter covers the premaculopathy, early maculopathy, established maculopathy, advanced maculopathy, final-stage maculopathy, mechanism of chloroquine toxicity, corneal deposits, visual field testing, color vision, electrooculogram, and electroretinogram and multifocal electroretinogram. Early maculopathy is defined by visual impairment (including some reduction in visual acuity). On ophthalmoscopy, the typical “Bull’s eye” maculopathy can be seen associated with impaired visual acuity and central visual field defects. Advanced maculopathy is characterized by marked atrophy of retinal pigment epithelium (RPE) and a visual acuity of or less than 20/200.