Retina and nerve fiber layer thickness in eyes with thyroid-associated ophthalmopathy

Background: Thyroid-associated ophthalmopathy (TAO) is an inflammatory disease that affects the thyroid gland and the eye orbit. Of patients with TAO, 3%–5% have severe sight-threatening disease due to optic neuropathy. Optical coherence tomography (OCT), the non-invasive imaging technology that yields high-resolution cross-sectional images of the retina, provides qualitative and quantitative data on the retina. Objectives: To apply this technique to quantitatively assess retinal nerve fiber layer (RNFL) and macular ring thicknesses in healthy subjects and in patients with TAO to determine their relationship to the severity of the orbital disease. Methods: the study group comprised all patients in the ophthalmology clinic who were diagnosed with TAO and underwent OCT imaging as part of their ocular examination; and healthy patients who volunteered to undergo OCT examination served as controls. Results of the complete ophthalmologic examination and OCT findings were collected from medical files, including the thickness of the RNFL and the macula. Results: The study comprised 21 patients and 41 healthy controls. TAO patients exhibited RNFL thickening and inner macula thinning compared to healthy subjects. Mean RNFL thickness was correlated with the severity of the orbital disease. Conclusions: The OCT findings suggest that the retina is involved in TAO, probably as early as the subclinical stage. This highlights the ability of OCT to identify retinal changes earlier and far more accurately than is detected today, enabling earlier diagnosis and more timely treatment to prevent severe visual sequelae.