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Adrian Tsang, Gianni Virgili, Ange-Lynca Kantungane, Chloe Gottlieb, Stuart G Coupland; A Novel Multifocal Electroretinography Stimulus for Detecting Hydroxychloroquine Retinal Toxicity.. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5957.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate a novel 5-ring multifocal electroretinogram (mfERG) as a screening test for detecting hydroxychloroquine (HCQ) retinopathy.
A stratified case-control study of consecutive patients referred to the University of Ottawa for HCQ retinopathy screening from July to September 2018 underwent mfERG testing using a novel 5-ring stimulus and 61-hexagon stimulus. Patients with amblyopia, high myopia or hyperopia, retinal disease, and prior retinal surgery were excluded. mfERG parameters were compared between protocols and against cumulative dose (CD), dose by real body weight (RBW), and duration of HCQ therapy. Ring P1 amplitudes (R1-R5) and ring ratios (R1-R4/R5) were collected for each stimulus protocol. Stata 15.1 was used to perform the regression analyses, and to compute Spearman correlation coefficients.
24 eyes (10 patients, 2 controls) were included in the final analysis. The novel R2/R5 and, R2 and R3 amplitudes, were moderately correlated with the respective R2/R5 (r= 0.422, p=0.040), and R2 (r= 0.434, p=0.034) and R3 (r= 0.429, p=0.036) amplitudes of the 61-hexagon stimulus. The novel R2 amplitude was highly correlated with CD (r=-0.687, p<0.001), treatment duration (r=-0.687, p<0.001), and dose by RBW (r=-0.763, p< 0.001). Similarly, novel R2/R5 was highly correlated with CD (r= -0.743, p< 0.001), treatment duration (r= -0.743, p< 0.001), and dose by RBW (r= -0.567, p=0.004). The correlations between the 61-hexagon R2/R5 and HCQ risk factors also reached significance, but were not as robust. Linear regression analysis showed that CD may account for almost half of the variance in the novel R2/R5. (r2= 0.486, R2/R5 = 9.68063 + CD *-0.00286)
The 2016 AAO guidelines focused on the use of subjective functional and objective structural testing, and relegated mfERG based on a lack of accessibility. This pilot study describes a new 5-ring mfERG protocol specific for HCQ retinopathy screening and suggests equivalence to the 61-hexagon protocol at characterizing parafoveal function. This novel stimulus has a significantly shorter acquisition period and the ring design may be more sensitive to HCQ induced electrophysiologic change in the parafoveal region. Additional prospective cohort studies are needed to validate this novel stimulus which may decrease the resource burden associated with objective functional testing.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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