The hidden impact of smoking in thyroid eye disease: a link between selenium deficiency, autoimmunity, and retinal...

To investigate the impact of smoking on serum selenium levels, autoimmune activity, and macular microvascular density in patients with clinically inactive thyroid-associated orbitopathy (TAO), using optical coherence tomography angiography (OCTA).

This retrospective cross-sectional study included 44 patients with inactive TAO (24 smokers, 20 non-smokers) and 32 ageand sex-matched healthy controls. All participants underwent ophthalmologic evaluation and laboratory testing for thyroid hormones, selenium, and thyroid-stimulating immunoglobulin (TSI). Macular vessel density was measured using spectral-domain OCTA at the superficial capillary plexus, deep capillary plexus, outer retinal layer, and choriocapillaris. Clinical activity score (CAS) was used to assess disease activity. The collected data were analyzed statistically.

Smokers with TAO exhibited significantly higher CAS (p = 0.016) and TSI levels (p = 0.027), and lower serum selenium concentrations (p = 0.042) compared to non-smokers. Central superficial and deep capillary plexus densities were significantly reduced in smokers versus healthy controls (p = 0.029 and p = 0.017, respectively). No significant differences were observed between smokers and non-smokers within the TAO group, or in the outer retinal layer and choriocapillaris layers among all groups.

Smoking status was associated with lower selenium levels, higher TSI levels, and increased CAS. Furthermore, retinal microvascular attenuation detected by OCTA, even in the absence of clinical activity in TAO, may serve as a significant indicator of persistent vascular deterioration.