Proptosis in Dysthyroid Ophthalmopathy: A Case Series of 10,931 Japanese Cases

ABSTRACT Purpose. This observational case series investigated the occurrence and distribution of proptosis in Japanese patients with dysthyroid ophthalmopathy (DO). The relationship among lid retraction, lid swelling, and enlargement of extraocular muscles was also analyzed. Methods. From 1993 to 2002, 10 931 patients (2240 men and 8691 women, average age; 39.9 ± 14.0 years) with abnormal thyroid function were examined for proptosis. Proptosis was measured using a Hertel exophthalmometer, and lid swelling and retraction were classified. Orbital magnetic resonance imaging or computed tomography was used to quantify enlargement of the extraocular muscles. Results. Clinically significant proptosis (≥15 mm) was present in 74.2% patients and was classified as mild (15–17 mm, 39.1%), moderate (18–20 mm, 25.9%), or severe (>20 mm, 9.2%). The average exophthalmometer reading was 17.2 ± 3.2 mm, with proptosis less pronounced with age (p < 0.001) and more pronounced in men than women (18.2 ± 3.4 mm vs. 17.0 ± 3.1 mm; p < 0.001). Lid retraction was present in 57.7% of patients, lid swelling in 46.9%, and muscle enlargement in 40.8% of patients. Multiple regression analysis revealed proptosis was strongly correlated with a young age and the male gender, followed by extraocular muscle enlargement and lid retraction and swelling (p < 0.001). Conclusions. This study assessed the measurable features of proptosis in Japanese patients with DO and contributes to the understanding by correlating symptoms and signs of DO.