Purpose: To characterize functional and structural changes in hydroxychloroquine (HCQ) retinal toxicity after drug cessation.
Methods: Twenty-two patients (91% female; mean age 58.7 ± 11.4 years; mean duration of HCQ treatment 161.1 ± 90 months; mean dose 5.9 ± 1.9 mg/kg) with detected HCQ retinopathy were monitored for 6 months to 82 months after HCQ cessation with multimodal imaging including spectral domain optical coherence tomography and fundus autofluorescence imaging at 488 nm (standard) and 787 nm (near-infrared autofluorescence). Tests of visual function including visual acuity, Humphrey visual field testing, and multifocal electroretinography (mfERG) were performed. Study eyes were categorized into four separate severity stages by qualitative grading of spectral domain optical coherence tomography macular scans taken at the time of HCQ cessation. Changes in outcome measures between drug cessation and last follow-up visit were computed and compared between eyes of different severity stages.
Results: Study eyes (n = 44) were categorized based on optical coherence tomography criteria into: Stage 1 (subtle changes confined to parafoveal region; n = 14), Stage 2 (clear localized changes in parafovea; n = 17), Stage 3 (extensive parafoveal changes; n = 7), and Stage 4 (foveal involvement, n = 6). Visual acuity measurements across follow-up were stable in Stage 1 and Stage 2 eyes but decreased significantly in Stage 3 and 4 eyes. Humphrey visual field measures were also stable in stages 1 and 2 but deteriorated in Stage 3 eyes. mfERG testing demonstrated significant improvement in the R1/R2 ratio after HCQ cessation in Stage 1 eyes (mean change = -0.86 ± 0.79, P = 0.03) but did not change significantly in eyes of higher stages. Decreases in macular thickness in ≥1 of 9 Early Treatment Diabetic Retinopathy Study subfields on spectral domain optical coherence tomography were found in eyes of all stages, with Stage 2 eyes demonstrating thinning in most subfields (eight of nine subfields). In eyes with a measurable central foveal ellipsoid zone band island (9 of 17 Stage 2 eyes and 7 of 7 Stage 3 eyes), progressive decrease in the foveal ellipsoid zone band length was observed in 6 of 9 (67%) Stage 2 eyes and 6 of 7 (86%) Stage 3 eyes. Changes indicative of progressing retinopathy were detected in 17% of Stage 1 eyes, 46% of Stage 2 eyes, and 43% of Stage 3 eyes on standard fundus autofluorescence imaging, and in 17% of Stage 1 eyes, 38% of Stage 2 eyes, and 14% of Stage 3 eyes on near-infrared autofluorescence imaging.
Conclusion: Eyes with detected HCQ retinopathy do not demonstrate general stability in retinal structure and function after HCQ cessation but instead demonstrate a range of changes during follow-up whose magnitudes correlate with retinopathy severity at the time of cessation. After cessation, eyes with only subtle and localized retinopathy were mostly stable and may show some functional improvement, whereas more severely affected eyes continued to progress. These findings provide evidence that early detection and prompt cessation in HCQ retinopathy may be needed to arrest retinopathy progression and to optimize long-term outcomes.