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John Flatter, Phoebe Nguyen, Sean Donghyun Kim, Jennifer Liao, Ingrid U Scott, Jeffrey M. Sundstrom; Early Retinal Biomarkers of Hydroxychloroquine Toxicity on Spectral Domain Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1839.
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© ARVO (1962-2015); The Authors (2016-present)
Spectral domain optical coherence tomography (SD-OCT) in patients with hydroxychloroquine (HCQ) retinal toxicity has revealed inner and outer retinal layer thinning. This study investigates the location of retinal thinning relative to the fovea in eyes with HCQ retinal toxicity.
Chart review of all patients evaluated at an academic medical center from 2012 to 2017 with the diagnosis “long-term use of plaquenil”. Exclusion criteria include other retinal or optic nerve pathology. SD-OCT exams with automated macular retinal layer segmentation were performed using a Spectralis SD-OCT (Heidelberg Engineering, Inc.). Mean retinal layer thicknesses were recorded for each of nine subfields of the Early Treatment of Diabetic Retinopathy Study (ETDRS) macular grid. Subjects were divided into group 1 (HCQ use <5 years), group 2 (≥5 to <10 years), group 3 (≥10 years), and group 4 (clinically evident HCQ retinal toxicity). Retinal layer thicknesses were compared among groups.
Of the 835 patients identified, 535 were excluded for retinal or optic nerve pathology and 258 were excluded due to insufficient data, leaving 72 subjects for analysis. Groups 1 through 4 had 17, 23, 28, and 4 subjects, respectively. All retinal layers were thinner in group 4 versus groups 1, 2, and 3. There was a larger reduction in retinal thickness within the four central subfields (inner ring) than the four outer subfields (outer ring) of the ETDRS grid, primarily within inner retinal layers (ganglion cell-inner plexiform layer (GC-IPL), outer nuclear layer (ONL) and combined inner retina). Outer retinal layers had less thinning, but still showed preferential thinning of the inner versus outer ring. Temporal analysis of SD-OCT exams revealed groups 1 and 2 had significantly less thinning than groups 3 and 4 within the inner ring of the total retinal thickness, GCL-IPL, ONL and combined inner retina.
Retinal thinning in HCQ retinal toxicity occurs preferentially within inner retinal layers and within the central four subfields (inner ring) of the ETDRS grid. Retinal thinning patterns among patients on HCQ for >10 years without known retinal toxicity are more similar to patients with known toxicity than those on HCQ for <10 years. Tracking retinal layer thicknesses within the ETDRS grid with application of ring ratio analysis may be a valuable tool in the early detection of HCQ retinal toxicity.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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