Chloroquine induced macular toxicity in a patient later developing sector retinitis pigmentosa: a case report.

PURPOSE:To describe how underlying retinal diseases, such as retinitis pigmentosa, increase the risk of chloroquine-induced macular toxicity. METHODS:Observational case report. RESULTS:We present the case of a 57-year-old woman being annually followed-up in the Ophthalmology service due to a systemic treatment with chloroquine (CQ). The explorations were successive normal, until a 10:2 visual field (VF) shows central defects in both eyes. Despite CQ treatment is discontinued, 10:2 VF reveal slowly progressive macular defects. During follow-up, fundus examination disclosed bone spicules in the inferonasal middle periphery: the electroretinogram (ERG) shows slow amplitude responses under scotopic conditions and the electrooculogram (EOG) also shows pathological responses. Therefore, the diagnosis of sector retinitis pigmentosa plus chloroquine maculopathy is made. Currently, the slow but constant progression of both peripheral and central defects is evident, despite having discontinued CQ treatment more than 15 years ago. CONCLUSION:Underlying retinal diseases seem to increase the risk of photoreceptor damage when undergoing a toxic insult. Thus, we hypothesize a potential interplay between retinal dystrophies and toxic maculopathy induced by CQ, and the influence of each of them in the evolution and prognosis of the other.