Just How Common Is Hydroxychloroquine Retinopathy?

Viewpoint

How does this study change our management of patients who require HCQ? Four major clinical conclusions can be drawn:

1. 
   HCQ is being used more frequently and more broadly in multiple specialty areas. Even though the risk for HCQ toxicity is low, more cases of toxic retinopathy will develop as more patients begin treatment with this drug.
   
2. 
   HCQ retinopathy is almost four times as prevalent as previously estimated, but better imaging has also enhanced our ability to make this diagnosis. SD-OCT is widely available and can aid in the diagnosis of early retinopathy, allowing the drug to be discontinued before major damage occurs.
   
3. 
   The safe dose of HCQ is best determined by after consideration of daily dose and duration of use, the presence of kidney disease (which delays elimination of the drug), and actual body weight. A daily dose of 5.0 mg/kg appears to be relatively safe; only 2% of patients in this study developed retinopathy after 10 years at this dose. Duration of dose is also an important consideration, because almost 20% of patients receiving a low dose of HCQ developed retinopathy after 20 years of use.
   
4. 
   Tamoxifen plus HCQ is a dangerous duo for the retina. This study included 38 patients using both hydroxychloroquine and tamoxifen; of those patients, 12 (31.6%) developed retinopathy—a rate much higher than in any other subgroup.
   

Another recent study found that over one third of patients at high risk for retinopathy had never received diagnostic testing for retinal changes. As eye care providers, we need to disseminate our knowledge regarding the risks for HCQ to both our patients and the larger medical community. This will ensure that patients receive the best care possible.