Structural and Functional Characterization of the Retinal Effects of Hydroxychloroquine Treatment in Healthy Eyes.

Purpose: To evaluate the influence of hydroxychloroquine in visual field and retinal layer thickness.

Methods: This is a retrospective cross-sectional study. Patients taking hydroxychloroquine without signs of hydroxychloroquine retinopathy were included. Optical coherence tomography segmentation was used to obtain the ETDRS map thickness of each retinal layer. Groups were divided into short-term (< 5 years) and long-term (≥5 years) drug use.

Results: We included 93 eyes of 93 patients (short-term: 25 eyes; long-term: 68 eyes). The inner nuclear layer (INL) was thinner in the long-term group (32.86 ± 2.12 vs. 34.14 ± 2.37 μm; p = 0.014). Considering long-term cases, the parafoveal ganglion cell layer (GCL) showed an inverse correlation with cumulative dose (r = -0.37; p < 0.001). After adjusting for confounders, parafoveal ganglion cell complex thickness was associated with cumulative dose (β = -0.239; p = 0.011). The parafoveal outer retina and visual field indices were similar between groups and did not correlate with cumulative dose.

Conclusion: Hydroxychloroquine leads to progressive thinning of the parafoveal inner retina, particularly the INL and GCL. Visual field indices do not reflect the long-term effects of the drug.