Abstract
Purpose :
Albeit the introduction of spectral-domain optical coherence tomography (SD-OCT) modified screening facilities of Hydroxychloroquine (HCQ) retinopathy, the investigation of risk factors suggesting an early identification of retinal changes due to the drug is pivotal.
Methods :
In a retrospective observational manner a dataset of 27 eyes with clinical hydroxychloroquine toxicity were analyzed and compared to an age-, gender-, ethnicity-matched control group with no toxicity. However, both groups had a significant difference in means of cumulative HCQ dosage in gram. SD-OCT scans (Heidelberg Engineering, Heidelberg Germany) were analyzed and automatic retinal-layer segmentation performed. Subsequently, mean thickness values subdivided in full retina, ganglion cell layer (GCL), outer nuclear layer (ONL), photoreceptor layer, retinal pigment epithelium (RPE) and outer retinal layer (photoreceptor layer + ONL) were calculated and compared. Additionally, layers were categorized in center, middle ring and outer ring according to the ETDRS grid.
Results :
The conducted study highlights changes of retinal thickness in patients with clinical toxicity. When comparing full retina layer in the central subfield, results revealed significant difference between eyes with toxicity to control eyes (250.8 ± 26.1 versus 272.1 ± 23.6, p=0.011), while the categorical variable including the percentage of eyes with reduced retinal thickness did not outline any significance (7.4% vs. 0%, p=0.554). However, comparing middle and outer ring of the full retina layer did show significant difference in both calculations (292.3 ± 27 versus 332.8 ± 16.6, p <0.001 respectively 59.3% versus 7.4%, p=0.013 and 265.8 ± 31.6 versus 292.0 ± 14.9 respectively 57.7% versus 0%, p=0.011). Similar results were detected for the middle ring of GCL and ONL. The GCL showed a highly significant difference of retinal thickness in eyes with toxicity compared to control eyes (35.3 ± 15.2 versus 49.6 ± 3.9, p=0.001) which resulted in a GCL thinning of 51.9% in toxicity eyes compared to reference data.
Conclusions :
Our data elucidate the impact of the cumulative dosage in regard of retinal changes. We emphasize the importance of OCT imaging as a screening tool to quantify structural changes in the different retinal layers that might help to identify early changes for patients with HCQ retinopathy with no clinical manifestation at an early stage.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.