Detection and prevention of maculopathy associated with antimalarial agents

Rheumatologists use both chloroquine and hydroxychloroquine in the treatment of systemic arthritic and immune disease. Hydroxychloroquine is much more expensive but is better tolerated by patients. My experience in watching patients being switched from one drug to another suggests that chloroquine is more effective in some patients than is hydroxychloroquine. Reynes thought that a review of the literature suggests that chloroquine is more toxic at 250 mg/day as compared to 400 mg of hydroxychloroquine if dose is based on these dosages. This theory may be related, in part, to the observation by Raines and associates that chloroquine crosses the blood- retinal barrier whereas hydroxychloroquine does not. Patients should be assessed 6 months after starting antimalarials. Routine automated perimetry is not indicated. An appropriate examination would include visual acuity testing, color-vision testing, Amsler grid testing, and corneal assessment. Patients should be dosed on the basis of ideal body weight (not actual body weight) to reduce the incidence of macular toxicity. Patients with no risk factors should be examined no more than once a year.