Subclinical Thyroid Eye Alterations Detectable With Electroretinography

Subclinical thyroid-associated ophthalmopathy (TAO) can be detected by monitoring for functional alterations on pattern and multifocal electroretinogram in eyes that have macular thinning but no fundus changes, according to research published in International Ophthalmology. Researchers used optical coherence tomography (OCT) and electrophysiological studies (EPS) to evaluate these morphological and functional changes. 

In the cross-sectional study, all participants underwent a complete ophthalmological examination, proptosis evaluation, spectral domain OCT, and EPS (pattern electroretinogram [PERG] and multifocal electroretinograms [mfERG], and visual evoked potentials).

A total of 80 eyes of 80 participants (mean age, 46 years), 40 patients with TAO and 40 participants used as a control group, were included in the study. Among baseline demographic and ocular characteristics, the researchers noted only the best-corrected visual acuity was significantly different between the patient and control groups (mean logMAR, 0.20±0.24 vs 0±0; P <.001).  

With multiple regression analysis, the team discovered the most important predictors of central foveal thickness were the degree of proptosis (β=- 0.56; P =.03) and P50 amplitude (β=0.39; P =.01) and the most important predictors of average RNFL thickness were duration of the disease (β=0.67; P =.004) and clinical activity score (β=-0.81; P <.001).

“Macular thinning along with functional alterations noticed by PERG and mfERG could be associated with subclinical retinopathy in TAO cases in the absence of fundus abnormalities,” the researchers report.

Limitations of the study included the small sample size, lack of antithyroid antibody testing, and lack of evaluation of the retinal microvasculature.