Prolonged hydroxychloroquine (HCQ) use, as in management of systemic lupus erythematosus or rheumatoid arthritis, can also cause damage to the outer retina known as HCQ retinopathy. Researchers from Korea suggest a retinal thickness deviation map generated from swept-source OCT (SS-OCT) images may be a helpful tool in detecting retinal damage caused by HCQ toxicity.

The retrospective cohort study enrolled 1,192 Korean patients with a history of HCQ treatment, including 881 (1,723 eyes) in a discovery set and 311 (591 eyes) in a validation set. Patients were screened for retinal toxicity using SS-OCT, fundus autofluorescence and standard automated perimetry.

According to the 2016 American Academy of Ophthalmology guidelines, HCQ retinopathy was diagnosed by the presence of abnormalities on one or more objective structural tests alongside corresponding visual field defects.

The investigators conducted 12x9mm² macular volume SS-OCT scans, and retinal thickness deviation maps were automatically generated using built-in software.

The retinal thickness deviation map showed the following abnormal patterns in eyes with HCQ retinopathy: pericentral (36%) or parafoveal ring (6.1%), mixed-ring (34.2%), central island (13.2%) and whole macular thinning (10.5%).

Additionally, maps that showed one of the five characteristic patterns in both eyes yielded the greatest diagnostic performance: sensitivity/specificity of 98.2%/89.1% and 100%/87.5% when applied to the discovery and validation set data, respectively. Moreover, the area of abnormal pixels on the retinal thickness deviation map was significantly correlated with the mean deviation and pattern standard deviation on the 30-2 visual field in eyes with HCQ retinopathy.

The map may provide a quick, objective assessment of the damaged area and can be widely used for HCQ retinopathy screening, the researchers noted. The map also has the potential as a screening or diagnostic tool for specific retinal diseases that show characteristic patterns of changes in retinal thickness, they added.