Clinical features of dysthyroid optic neuropathy: a European Group on Graves' Orbitopathy (EUGOGO) survey

Abstract

Background: This study was performed to determine clinical features of dysthyroid optic neuropathy (DON) across Europe. Methods: Forty seven patients with DON presented to seven European centres during one year. Local protocols for thyroid status, ophthalmic examination and further investigation were used. Each eye was classified as having definite, equivocal, or no DON. Results: Graves' hyperthyroidism occurred in the majority; 20% had received radioiodine. Of 94 eyes, 55 had definite and 17 equivocal DON. Median Clinical Activity Score was 4/7 but 25% scored 3 or less, indicating severe inflammation was not essential. Best corrected visual acuity was 6/9 (Snellen) or worse in 75% of DON eyes. Colour vision was reduced in 33 eyes, of which all but one had DON. Half of the DON eyes had normal optic disc appearance. In DON eyes proptosis was . 21 mm (significant) in 66% and visual fields abnormal in 71%. Orbital imaging showed apical muscle crowding in 88% of DON patients. Optic nerve stretch and fat prolapse were infrequently reported. Conclusion: Patients with DON may not have severe proptosis and orbital inflammation. Optic disc swelling, impaired colour vision and radiological evidence of apical optic nerve compression are the most useful clinical features in this series.

Quantification of Orbital Apex Crowding for Screening of Dysthyroid Optic Neuropathy Using Multidetector CT

“…In our study, although the subjective orbital apex CI detected DON with 80.6% sensitivity for scores 1 or 2, none of the 36 affected orbits presented grade 3 apical crowding. These findings are remarkably different from previous studies using the Nugent subjective score to detect DON, 1,3,9,15 probably due to differences in subjective criteria for defining and grading apical crowding. While it seems clear that the Nugent apical crowding score is useful to raise suspicion of the presence of DON, it does not provide a clear definition of the position along the orbit where the coronal plane is used to determine it, nor does it provide a clear differentiation between grades 1, 2, and 3.…”

“…16 A recent multicenter study found apical muscle crowding in 49 of 56 orbits with DON. 1 In another study, severe optic nerve crowding was retrospectively noted in 80% of orbits (16 of 20) with optic neuropathy compared with 29% of orbits without DON (10 of 34). No orbits with optic neuropathy scored lower than grade 2.…”

“…The theory is based mostly on CT imaging studies confirming the presence of orbital apex crowding in most patients with DON. 10,12,13,18,19 Because of its great importance in DON, apical crowding is quantified with a score first described by Nugent et al 15 and reproduced by many other authors, 1,3,7,9,16 which grades the effacement of the perineural fat as 0 (none), 1 (up to 25%), 2 (25%-50%), or 3 (greater than 50%). 15 Using this method, Nugent et al found severe apical orbital crowding (grade 3) in 12 of 18 orbits with DON but in only 16 of 124 orbits without DON.…”

“…GO may occur before, during, or after the onset of hyperthyroidism or, less frequently, in euthyroid or hypothyroid patients. 1 The enlargement of the extraocular muscles is responsible for most of the debilitating manifestations of the disease, including proptosis, diplopia, congestive signs, and DON. [2][3][4][5] DON is a serious complication of GO occurring in 3.4% of patients, 6 almost always as a result of optic nerve compression at the orbital apex by enlarged extraocular muscles.…”

“…9 CT is the preferred imaging technique for investigating DON. 1 Several studies have tested the ability of CT parameters (linear, 3,[9][10][11] area, and volume [12][13][14] measurements of the orbital muscles) to facilitate the diagnosis of DON. Most of these studies used axial and direct or reformatted coronal images acquired with conventional CT scanners, and calculations were often performed manually from hard copies of the scans.…”