Spectral domain optical coherence tomography detects early stages of chloroquine retinopathy similar to multifocal electroretinography, fundus autofluorescence and near-infrared autofluorescence

Aims: To compare spectral domain optical coherence tomography (sdOCT) with melanin-related near-infrared fundus autofluorescence (NIA, excitation 787 nm, emission >800 nm), lipofuscin-related fundus autofluorescence (FAF, excitation 488 nm, emission >500 nm) and multifocal electroretinography (mfERG) in patients with long-term chloroquin (CQ) treatment. Methods: Eight patients with 5.5-22 years of CQ treatment underwent clinical examination, mfERG recording, FAF and NIA imaging using a confocal scanning laser ophthalmoscope (Heidelberg Retina Angiograph 2) and sdOCT imaging (Spectralis OCT Heidelberg Retina Angiograph). Results: In three patients, all test results were normal after 5.5-16 years of CQ treatment. Five patients presented with variably progressed CQ retinopathy (10-22 years of treatment) and abnormalities in all tests. In the mildest case, pericentral reduction in mfERG amplitudes corresponded to increased pericentral FAF, reduced pericentral NIA and pericentral interruption of the photoreceptor inner/outer segment junction in the sdOCT. In all sdOCT scans, the outer nuclear layer thickness was reduced. More severe cases showed preserved subfoveal photoreceptors and function with marked changes in all examinations towards the periphery. The most severe case presented with additional loss of subfoveal photoreceptors. Conclusion: MfERG, FAF, NIA and sdOCT detect early stages of CQ retinopathy. Loss of outer nuclear layer thickness might be the earliest indicator of CQ retinopathy.