Medications Damaging Retinal Pigment Epithelium and Photoreceptor Complex-1: Pathogenesis, Diagnosis, and Treatment (Chloroquine/hydroxychloroquine)

Hydroxychloroquine and chloroquine are frequently used in the treatment of rheumatic and parasitic diseases as a result of their immunomodulatory effects. Due to their high plasma distribution volumes, they cause irreversible side effects by accumulating in the tissues containing melanin following long-term use. Currently, these side effects can be detected before they reach advanced stages (bull’s eye maculopathy) thanks to new developments in diagnosis and imaging methods. Patients with concomitant tamoxifen use, impaired renal function, a dose of hydroxychloroquine greater than 5mg per kg per day or the dose of chloroquine greater than 2,3 mg per kg per day, older age, long-term use (10-25 years) have increased risk of retinopathy. Patients should be reviewed annually thereafter whilst on therapy and they should undergo imaging with optical coherence tomography (OCT), widefield fundus autofluorescence imaging (FAF), and 10-2 visual field testing at each monitoring visit. If the evidence of toxicity cannot be completely excluded patients should undergo multifocal electroretinography (mfERG). Of the tests used in the diagnosis of hydroxychloroquine/chloroquine retinopathy, mfERG has the highest sensitivity and specificity, followed by SD-OCT and 10-2 visual field tests, respectively. Once the precise signs of early retinopathy are detected, the decision to stop the medication should be taken in conjunction with prescribing physician. It should not be forgotten that retinopathy findings will progress even if the treatment is ceased. Following the screening, guidelines allow early detection of retinopathy before leading to irreversible retinal damage.