Longitudinal Retinal Changes Induced by Hydroxychloroquine in Eyes without Retinal Toxicity

Introduction: This study aimed to evaluate the longitudinal changes in retinal layer thickness in patients treated with hydroxychloroquine without retinal toxicity. Methods: This is a longitudinal retrospective study of patients taking hydroxychloroquine followed in a hydroxychloroquine retinal toxicity screening program of a tertiary hospital between January 2010 and April 2019. Patients who performed 2 optical coherence tomography (OCT) scans at least 1 year apart were included. All subjects with hydroxychloroquine suspected or confirmed retinal toxicity, glaucoma, retinal pathology, or poor segmented images were excluded. Spectral-domain optical coherence tomography (Spectralis HRA-OCT, Heidelberg) was used to evaluate the macular area. Automatically segmented ETDRS retinal thickness maps were compared between the first and the last OCT evaluation available. Full retina (FR), inner retina (IRL), ganglion cells (GCL), inner nuclear (INL), and outer retina (ORL) layer thicknesses were measured in the foveolar, paracentral, and peripheral area. Results: The population included 144 eyes of 144 patients. The mean interval between OCT scans was 38.1 +/- 18.4 months, and the mean cumulative dose was 406.9 +/- 223.9 g. Foveolar (p = 0.040, p = 0.006, and p = 0.001, respectively) and paracentral (p = 0.006, p = 0.001, and p = 0.005, respectively) FR, IRL, and GCL decreased overtime. No differences were found in INL or ORL. A very weak correlation was found between age and foveal IRL change overtime (p = 0.037; R = 0.175), as well as between the hydroxychloroquine time of use and foveal GCL variation (p = 0.032; R = 0.179). Conclusion: Hydroxychloroquine was found to cause progressive thinning of the inner retinal layers, specifically in the GCL of the foveolar and paracentral areas, but no changes were observed in the outer retina.