Early screening opportunities for retinal toxicity
Hydroxychloroquine (HCQ) and its predecessor, chloroquine (CQ) are antimalarial drugs with well-established benefits for treating rheumatoid arthritis, lupus, and other connective tissue and skin disorders. Extensive research has shown long-term usage of either drug to be associated with retinal toxicity. Early detection of HCQ/CQ retinopathy is imperative to minimize the risk of any associated vision loss.
Visual electrophysiology for retinal toxicity
The American Academy of Ophthalmology (AAO) recommends the use of objective testing to screen for retinal toxicity. Multifocal electroretinography (mfERG), a test defined by the International Society for Clinical Electrophysiology of Vision (ISCEV), offers an objective assessment of retinal function in patients treated with HCQ/CQ. A 2019 study suggests that while spectral-domain optical coherence tomography (sdOCT) can detect retinal toxicity, mfERG demonstrates greater sensitivity to retinal dysfunction that may precede structural abnormalities. Also, mfERG can be useful in confirming the absence of retinal toxicity when perimetry or other tests detect abnormalities.
One-minute toxicity screening
A novel 4-ring mfERG was developed for the detection of parafoveal functional loss, such as that which typically presents from retinal toxicity due to Plaquenil and related medications. This test is done within one minute and is ideally suited as an ophthalmic screening test for at-risk patients.
References
Dettoraki M, Moschos MM. The Role of Multifocal Electroretinography in the Assessment of Drug-Induced Retinopathy: A Review of the Literature. Ophthalmic Res. 2016;56(4):169-177. doi: 10.1159/000446321. Epub 2016 Jun 29. PMID: 27351191.
Marmor MF, Kellner U, Lai TY, Melles RB, Mieler WF; American Academy of Ophthalmology. Recommendations on Screening for Chloroquine and Hydroxychloroquine Retinopathy (2016 Revision). Ophthalmology. 2016 Jun;123(6):1386-94. doi: 10.1016/j.ophtha.2016.01.058. Epub 2016 Mar 16. PMID: 26992838.
Tsang AC, Ahmadi S, Hamilton J, Gao J, Virgili G, Coupland SG, Gottlieb CC. The Diagnostic Utility of Multifocal Electroretinography in Detecting Chloroquine and Hydroxychloroquine Retinal Toxicity. Am J Ophthalmol. 2019 Oct;206:132-139. doi: 10.1016/j.ajo.2019.04.025. Epub 2019 May 10. PMID: 31078540.
Tsang A, Kanda P, Gottlieb C, Virgili G, Kantungane L, Coupland S. A novel 5-ring multifocal electroretinography stimulus for detecting hydroxychloroquine retinal toxicity. Doc Ophthalmol. 2022 Apr;144(2):117-124. doi: 10.1007/s10633-021-09858-4. Epub 2021 Nov 11. PMID: 34762206; PMCID: PMC9033700.