Optical Coherence Tomography Thickness Measurements of the Extraocular Rectus Muscle Tendons in Graves' Ophthalmopathy

Purpose: To examine extraocular rectus muscle tendons in patients with Graves' ophthalmopathy using optical coherence tomography (OCT). Methods: This was a cross-sectional observational study conducted with 55 healthy controls, 45 patients with clinically inactive Graves' ophthalmopathy, and 12 patients with clinically active Graves' ophthalmopathy. Scanning was performed at the 3- and 9-o'clock positions. The medial rectus tendon thickness was measured at 7.2 and 9.2 mm from the limbus and the lateral rectus tendon thickness was measured at 8.5 and 10.5 mm from the limbus. Results:The 9.2-mm medial rectus, 8.5-mm lateral rectus, and 10.5-mm lateral rectus tendons were thicker in the inactive Graves' ophthalmopathy group than the control group (240 +/- 70, 231 +/- 63, and 228 +/- 54 mu m vs 201 +/- 71, 199 +/- 53, and 200 +/- 32 mu m, respectively; P <= .011), whereas the 8.5-mm lateral rectus and 9.2-mm medial rectus tendons were thicker in patients with active Graves' ophthalmopathy than patients with inactive Graves' ophthalmopathy (274 +/- 77 and 283 +/- 68 mu m vs 231 +/- 63 and 240 +/- 70 mu m, respectively; P <= .048). A correlation was detected between lateral rectus and medial rectus tendon thicknesses and the Graves' ophthalmopathy clinical activity score (R = 0.252, P = .035; and R = 0.291, P= .013, respectively). Conclusions: OCT emerged as an accurate method for measuring medial rectus and lateral rectus tendon thicknesses in patients with Graves' ophthalmopathy. The imaging tool was able to detect thicker horizontal rectus tendons in patients with inactive Graves' ophthalmopathy than in controls, and in patients with active compared to inactive disease.