Assessment of parafoveal cone density in patients taking hydroxychloroquine in the absence of clinically documented retinal toxicity

{PurposeTo measure cone density in patients taking hydroxychloroquine (HCQ), with no clinical evidence of maculopathy. MethodsPatients visiting for HCQ macular toxicity screening in the Besancon University Hospital Ophthalmology Department (France) were studied. They underwent routine examination including spectral-domain optical coherence tomography, fundus autofluorescence and multifocal electroretinogram to detect HCQ-induced retinal toxicity. Cone metrics (density, spacing and percentage of cones with six neighbours) were obtained using an adaptive optics camera (RTX1, Imagine Eyes, Orsay, France). The region of interest corresponded to a 0.3 degrees x0.3 degrees square placed nasally and temporally at 2 degrees of eccentricity from the fovea. ResultsForty eyes of 23 patients were studied. The majority of the patients (21/23) were female. They were aged from 25 to 60years (mean ageSD: 40.1years +/- 10). The cumulative dose for HCQ ranged from 24 to 2160g (777 +/- 558g). None of them displayed HCQ toxicity on screening tests. Bivariate analysis showed moderate cone loss with escalating doses of HCQ (linear regression, r(2)=0.23