Abstract
Purpose :
Early detection of hydroxychloroquine(HCQ) retinopathy is important. Prior studies have suggested that HCQ primarily damages photoreceptors, with subsequent disruption of retinal pigment epithelium and choroidal thinning. The aim of this study was to determine whether changes of outer retinal layer(ONL) thickness and choroidal thickness might signal impending toxic effects of HCQ before development of retinopathy.
Methods :
We included patients who were screened for HCQ retinopathy, and followed for ≥ 12 months. Based on visual field, optical coherence tomography(OCT) and autofluorescence, patients with no retinopathy were collected. During follow-up period, HCQ was continued in 121 patients (continued group), and stopped in 25 patients due to non-retinotoxicity reasons (discontinued group).
Using OCT images, ONL thickness was obtained from fovea, inner ring and outer ring of the Early Treatment of Diabetic Retinopathy Study(ETDRS) grid. Subfoveal choroidal thickness(SFChT) was measured from EDI-OCT. The thicknesses were measured at baseline, and repeated at least 1 year apart. Comparison was made between the baseline OCT and the last OCT available in each group.
Results :
At baseline, mean dose/kg were 3.90mg/kg, 4.70mg/kg, and duration of medication 154.2months, 90.5months, in ‘continued’ and ‘discontinued’ group, respectively. There were no significant differences in thicknesses between ‘continued’ and ‘discontinued’; mean ONL thicknesses of foveal(87.9, 88.1um), inner ring(66.5, 64.5um), outer ring(54.2, 51.6um) and mean SFChT(246.6, 229.9um).
Over the follow-up period, 'continued’ group(mean of 37.4months) showed a progressive ONL thinning in outer ETDRS ring(54.2 to 53.0um, p=0.000), and progressive decrease in SFChT(246.6 to 218.7um, p=0.000). ‘Discontinued’ group(mean of 33.3months) also showed a significant ONL thinning in outer ETDRS ring(51.6 to 50.1um, p=0.001), but, interestingly, showed a significant increase in SFChT(229.9 to 239.2um, p=0.024) after cessation of HCQ medication.
Conclusions :
ONL thinning was observed progressively in patients taking HCQ prior to development of retinopathy. Although choroidal thickness also decreased while HCQ treatment, thinning was partially recovered following early discontinuation of HCQ. We suggest the measurements of ONL and choroidal thickness might be used for early detection of HCQ retinal toxicity.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.