Chloroquine is a potent drug used for the treatment of various diseases, including malaria and a range of connective tissue disorders. Chloroquine retinopathy is an important complication that may appear even years after cessation of the drug, presenting with impaired visual acuity, central vision loss and progressive damage that could result in irreversible blindness. A detailed patient history that confirms chloroquine use is essential, while advanced ophthalmologic methods must be employed to assess the status of the retina.
Chloroquine (and hydroxychloroquine) are drugs with still incompletely understood mechanisms of action, but their ability to alter intracellular pH, suppress CD4+ T-cells activity and promote the activation of CD8+ T-cells makes them useful in an array of disorders of different etiologies  . In the tropical parts of the world, chloroquine is a potent antimalarial agent (both in therapy and in prophylaxis), whereas autoimmune connective tissue diseases, such as systemic lupus erythematosus (SLE), dermatomyositis, rheumatoid arthritis (RA), and Sjogren's syndrome are also treated with chloroquine, primarily to achieve long-term suppression    . Its affinity for pigmented tissues , however, is the principal reason why chloroquine retinopathy is one of the most important, but also most feared complications when using this drug. As a consequence of progressive chloroquine accumulation in the retinal pigment epithelium and the retinal neurons  , where it exerts its toxic effects, various visual symptoms may be encountered even years after cessation of drug use, as the body excretes chloroquine through urine for a long period of time . The "bull's eye" maculopathy is considered to be a pathognomonic finding of chloroquine retinopathy, manifesting as loss of central vision, while night blindness, reduced visual acuity, photoaversion, reading difficulties, and other visual deficits (eg. color blindness, scotomas) are some of the most frequent symptoms reported in chloroquine retinopathy     . In a significant proportion of individuals who develop this complication, progression toward blindness in an irreversible fashion can be observed, due to the severe damage of photoreceptors and the retinal epithelium .
Because chloroquine retinopathy might result in blindness without proper monitoring and follow-up, the appearance of visual complaints must alert the physician to conduct a detailed patient history to confirm either current or previous use of chloroquine, regardless of the underlying etiology. Furthermore, many reports have stressed the need for continuous follow-ups and screening of individuals who are taking chloroquine with several ophthalmologic procedures    . Firstly, a meticulous physical examination that includes visual field and acuity testing, together with anterior fundoscopy, should be the first step in workup, where typical findings of chloroquine retinopathy (pigmentary changes, bull's eye maculopathy, retinal degeneration, atrophy of the optic nerve) may be initially seen  . Once a presumptive diagnosis is made, various specialized procedures are used for confirming the clinical suspicion. Spectral-domain optical coherence tomography (SD-OCT), multifocal electroretinography, and fundus autofluorescence (FAF) are recommended for screening and detection of retinal changes associated with chloroquine retinopathy   .