• Used to prevent or treat malaria infections caused by mosquito bites
• Belongs to a class of medications known as disease-modifying antirheumatic drugs (DMARDS)
• Main side effects are gastrointestinal upset, skin rash, headache and ocular toxicity
• Toxic effects negatively impacts the cornea, ciliary body and retina
Early toxicity may be asymptomatic, patients with more advanced stage of toxicity may complain of color vision changes or paracentral scotomas
Advanced Hydroxychloroquine toxicity presents as a bulls eye maculopathy
• Corneal toxicity presents as an intraepithelial deposition of the drug into the cornea. Which rarely affects vision
• Hydroxychloroquine retinopathy is most influenced by daily dose, length of use and cumulative dose over time
• Risk of toxicity is least with less than 6.5mg/kg/day for Hydroxychloroquine and 3 mg/kg/day for chloroquine.
• High risk patient is one who receives greater than 6.5 mg/kg/day for more than 5 years with coexisting retinal disease
Hydroxychloroquine retinopathy causes destruction of macular rods and cones with sparing of foveal cones – this pattern provides the typical bulls eye appearance.