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Yasha Modi, Vishal Parikh, Adrian Au, Rishi P Singh; Hydroxychloroquine Screening and Toxicity: A Comparison Between Screening Modalities. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1792.
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© ARVO (1962-2015); The Authors (2016-present)
We identify patients with hydoxychloroquine (HCQ) toxicity and compare detection rates between different screening modalities as suggested by the 2011 updated screening guidelines.
This was a retrospective, observational study, evaluating patients taking HCQ between 2011 and 2014 at a single academic institution.
A total of 756 patients were screened for HCQ toxicity. Twenty (2.6%) patients had abnormal screenings and 12 (1.6%) were determined to have HCQ toxicity by the treating physician. While 9/12 (75%) were appropriately receiving less than 6.5 mg/kg (ideal body weight)/day, 8/12 (66.7%) had received a lifetime dose exceeding 1 kg. Five of the 12 (41.7%) were symptomatic on presentation with 3 reporting intermittent blurry vision and 2 reporting persistent blurry vision. Two presented with classic bulls eye maculopathy and 8/12 (66.7%) had nonspecific retinal pigment epithelial (RPE) changes. Twelve (100%) had an abnormal SD-OCT demonstrating parafoveal loss or thinning of the ellipsoid zone, external limiting membrane, and outer plexiform layer. Eleven of 12 patients had a HVF 10-2, of which 4/11 were unreliable. Eight/11 (72.7%) had paracentral defects; 3/11 (27.3%) had central depression. FAF was performed in 9/12 patients and 8/9 (88.9%) demonstrated hypoautofluorescence patterns while the remaining 1 had a normal autofluorescence pattern. Multifocal ERG was not performed in any of the 12 patients.<br /> <br /> At diagnosis, 1/12 had previously stopped HCQ and 11 were encouraged to stop immediately.
HCQ toxicity is a rare entity. As only 42% were symptomatic on presentation, early detection with sensitive screening modalities is essential. SD-OCT demonstrated the most consistent abnormalities with 100% presenting with characteristic parafoveal outer retinal thinning. While the subjective component of HVF may yield unreliable results, all patients in this study had either paracentral visual field loss or central depression. Fundus autofluorescence did not uniformly demonstrate a deficit and mfERG was not performed in any patient with toxicity.<br /> <br /> Given the recommendations of the 2011 screening guidelines, it is reasonable to use SD-OCT as an anatomic test coupled with HVF 10-2 as a functional test to assess maculopathy. FAF may be better utilized as a confirmatory test rather than a stand-alone screening test as not all patients demonstrated abnormal findings.
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