• 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.