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Anh-Danh Phan, Jennifer Eikenberry, Lissa McNulty; The early visual changes with hydroxychloroquine (HCQ) usage detected with multifocal ERG (mfERG) versus spectral domain OCT (SDOCT) and 10-2 field testing. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2805.
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© ARVO (1962-2015); The Authors (2016-present)
The AAO recently updated its recommendations on screening for HCQ retinopathy. The current goal of toxicity screening, typically performed after 5 years of usage, is to detect early macular functional or anatomic injury to avoid further visual damage with chronic therapy. New testing modalities, such as mfERG and SDOCT, are reportedly more sensitive in detecting macular injury. The new recommendations advise usage of these new technologies when available or when the 10-2 field testing shows defect. The purpose of this study is to report on the early changes of HCQ usage observed with these new modalities compared to 10-2 field testing.
Retrospective, comparative chart and diagnostic testing review of six subjects undergoing HCQ therapy of less than 5 years duration. Baseline examination included functional 10-2 field and objective mfERG/SDOCT testing. Repeat examinations over the ensuing months (differing from the AAO recommendations) involved serial 10-2 field and mfERG/SDOCT testing. Comparisons between baseline and each follow-up visit were performed. Outcome measures were testing changes/progression.
Examination started less than 1 month through 69 months from initiation of HCQ therapy. All subjects demonstrated dramatic changes on mfERG testing: diminution of B-wave amplitude in particular paracentral; eccentric shifting of the hill of vision; and/or supranormal total response. Correspondingly, SDOCT subfield plot/cross section paracentral thinning occured afterwards, showing progression with time. 10-2 field defects also occurred after mfERG changes. HCQ dosages ranged from 200 to 400 mg per day.
On less than 5 years of HCQ usage, the visual electrophysiologic changes are consistent and dramatic. It is uncertain whether these beginning changes signify transient hypersensitivity of the macular photoreceptors versus precursor of injury to at-risk photoreceptors with long-term usage or identify individuals susceptible to earlier retinopathy. SDOCT also detects progression and may provide even earlier detection. The current goal of HCQ toxicity screening, in which early macular photoreceptor damage has already occurred and is permanent, needs to consider the technological advances afforded by sensitive new testing modalities and accordingly may need to be modified to avoid even early macular damage.
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