Hydroxychloroquine (HCQ) may alter parafoveal retinal layers and subfoveal and parafoveal choroidal thicknesses despite failure to detect retinal toxicity through optical coherence tomography (OCT), researchers found in a study published in Photodiagnosis and Photodynamic Therapy.

Since patients with HCQ toxicity may remain asymptomatic until severe stages of damage, researchers investigated whether HCQ treatment impacted retinal layer, peripapillary retinal nerve fiber layer, and choroidal thicknesses in patients whose OCT exams did not identify retinal toxicity.

The team included 49 patients treated with HCQ and 39 healthy controls in the study. They stratified patients using HQC into 2 subgroups. Group 1 consisted of participants  who had undergone HCQ treatment for less than 5 years (n=29, 24.2±14.8 months of use, 248.4±181.6 grams cumulative dose) and group 2 participants took HCQ for at least 5 years (n=20, 99.3±48.3 months of use, 896.4±480.7 grams cumulative dose). Researchers performed a comprehensive eye exam and OCT imaging on all participants.

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The investigators noted that inferior 1-3 mm retinal nerve fiber layer (RNFL) thickness was lower in both group 1 and 2 compared with the control group (P =.048 and P =.007, respectively). Group 2 had significantly lower nasal 1-3 mm RNFL, temporal 1-3 mm ganglion cell layer (GCL), and temporal 1-3 mm inner plexiform layer (IPL) thicknesses compared with the control group (P =.007, P =.009, and P =.006, respectively). Group 1 had significantly higher temporal 1-3 retina pigment epithelium (RPE) thickness compared with the control group (P =.003).

Inferior 1-3 mm RNFL thickness was associated with nasal 1-3 mm RNFL thickness, temporal 1-3 mm GCL thickness, and temporal 1-3 IPL thickness. Nasal 1-3 mm RNFL thickness was associated with temporal 1-3 mm GCL thickness and temporal 1-3 mm IPL thickness, while temporal 1-3 mm GCL thickness was associated with temporal 1-3 IPL thickness (P ≤.002 for all).

Group 1 and group 2 had lower subfoveal choroidal thicknesses compared with the control group (P =.042 and P =.009, respectively) while temporal 1000 μm thicknesses were lower in group 2 compared with the control group (P =.018).

“HCQ use may cause parafoveal retinal layer alterations and also subfoveal and parafoveal choroidal thickness alterations even without apparent retinal toxicity in OCT,” according to the researchers.

Limitations of the study include a lack of visual field examination or multifocal ERG testing.


Polat OA, Okçu M, Yilmaz M. Hydroxychloroquine treatment alters retinal layers andchoroid without apparent toxicity in optical coherence tomography. Photodiagnosis and Photodynamic Therapy. Published online March 11, 2022. doi:10.1016/j.pdpdt.2022.102806