Early onset hydroxychloroquine retinopathy and a possible relationship with blood level: comment on the article Petri et al

Petri et al reported that higher hydroxychloroquine (HCQ)　blood levels predicted later retinopathy (1) . However, in a recent case-control study, the blood level was not associated with retinopathy(2). The inconsistency may arise from dose adjustment over the years and the timing of blood level testing.