Abstract
Purpose :
Thyroid eye disease (TED) is a debilitating and disfiguring autoimmune condition which affects 50% of people with Graves disease. Although the exact pathophysiology is unknown, enlarged extraocular muscles leading to lid retraction and proptosis are a hallmark of the condition. Orbital surgeons rely on three-dimensional imaging such as computed tomography and magnetic resonance imaging to assess the status of these muscles thereby exposing patients to radiation and claustrophobic environments. Anterior segment optical coherence tomography (AS-OCT) is a technology readily available in many clinics with the ability to capture high-resolution detail of many structures, including the extraocular muscles (EOM). Our hypothesis was that EOM in TED would be thicker based on AS-OCT measurements compared to healthy controls.
Methods :
A prospective cross-sectional study of 34 eyes was designed. The lateral rectus (LR), medial rectus (MR), superior rectus (SR), and inferior rectus (IR) muscle bellies of each eye were imaged using AS-OCT (Spectralis, Heidelberg, USA). Using the Spectralis analytical software, the thickness of the muscle bellies was measured (healthy LR/MR n = 18, TED LR/MR n = 16, healthy SR n = 9, TED SR n=5, healthy IR n = 9, TED IR n = 4). Statistical significance was shown using a two-tailed T- test to compare healthy vs TED for each group of recti muscles.
Results :
The mean LR muscle thickness in healthy controls was significantly different than in TED subjects (217.2 ± 65.2 μm vs 339.4 ± 67.3 μm; P<0.001). The mean MR muscle thickness in healthy controls was significantly different than in TED subjects (225.4 ± 60.6 μm vs 336.3 ±104.9 μm; P<0.005). The mean SR muscle thickness in healthy controls was significantly different than in TED subjects (134.3 ± 44.6 μm vs 305.8 ±100.2 μm; P<0.05). The mean IR muscle thickness in healthy controls was significantly different than in TED subjects (178.0 ± 42.1 μm vs 223.3 ± 26.1 μm; P<0.05).
Conclusions :
This study is the first of its kind in the United States to show that AS- OCT can detect differences in extraocular muscle thickness in TED compared to healthy controls. With further validation, AS-OCT may be an invaluable tool for clinicians to diagnose and monitor TED in patients with claustrophobia and without radiation exposure. Future studies will include assessment of therapy response.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.