Hydroxychloroquine Retinal Toxicity Detectable Earlier With OCT Technique

Hydroxychloroquine retinal toxicity may be identifiable before obvious retinal insult, according to research presented at the Association for Research in Vision and Ophthalmology (ARVO) 2023 Annual Meeting, held in New Orleans from April 23 to April 27, 2023. The researchers believe their quantitative, high-density optical coherence tomography (OCT) cluster analysis can detect photoreceptor thinning before formal diagnosis of hydroxychloroquine retinal toxicity, the report suggests, making current assessments inadequate. 

Hydroxychloroquine is commonly used as an autoimmune drug, but patients taking it must be monitored regularly for potential damage to the retina. Traditionally, that damage is observed via qualitative OCT evaluations of outer retinal thinning, according to the presenters. “This study uses quantitative, high-density OCT cluster analysis to examine whether photoreceptor changes occur prior to [hydroxychloroquine] retinal toxicity diagnosis.”

Researchers included 67 participants who used hydroxychloroquine and 134 participants who did not use hydroxychloroquine in the study. The propensity-score was matched by age, sex, and refraction and all study participants had normal macular health. The research team randomly selected 1 eligible eye per participant for the study. The study employed 2 graders who were blinded to participants’ group status to manually segment the outer plexiform layer (OPL) and outer nuclear layer (ONL) OCT borders, including Henle’s fiber layer (OPL/HFL/ONL) in the evaluation of potential hydroxychloroquine retinal toxicity. The researchers then evaluated topographic differences between the groups. 

When comparing participants using hydroxychloroquine vs those not using hydroxychloroquine, the researchers found 1 cluster (C₋₁) of significantly thinned OPL/HFL/ONL (-1.6 [-2.76, -0.44] µm, P <.01) with small effect size (-0.25). According to the report, the cluster of thinned OPL/HFL/ONL was primarily confined to the nasal quadrant (81.89% nasal vs 1% temporal quadrant area, P <.0001), and equally distributed in the superior and inferior quadrants (17.11% vs 17.56% respectively, P =.87).

Photoreceptor thinning prior to a formal diagnosis of hydroxychloroquine retinal toxicity can be detected using quantitative, high-density OCT cluster analysis, according to the presenters. “This suggests current qualitative assessment of photoreceptor integrity in clinical practice may be inadequate for detection of [hydroxychloroquine] retinal toxicity, and further implementation of quantitative measures could assist early detection.”