Consultant Medical Ophthalmologist (retired), Addenbrooke's Hospital, Cambridge, UK.
Department of Engineering, Cambridge University, Cambridge, UK.
Eye (Lond). 2019 Feb;33(2):244-253. doi: 10.1038/s41433-018-0302-1. Epub 2019 Jan 18.
The clinical features of thyroid eye disease are dictated by the orbit's compartmentalisation; particularly, the muscle cone, which is delimited by the rectus muscles, their inter-muscular septa and the posterior sclera. The cone is anchored to the orbit apex and contains the posterior globe, the muscle bellies, a fat pad, and the blood circulation, optic nerve, and CSF sheath. It is surrounded by mobile extraconal fat, retained by the orbital septum.Thyroid eye disease is caused by expansion of muscle bellies and fat within the cone. Mechanical properties of the cone determine that the disease partitions into three phases: circumferential expansion, with forward displacement of extraconal fat; axial elongation, with increasing cone pressure; impedance of posterior venous outflow, with cone oedema and venous flow reversal.Venous flow reversal can be observed in the conjunctival circulation. It is initially transient, accompanying rises in cone pressure caused by eye movements, but later becomes permanent. It is a useful clinical sign that locates diseased muscles and anticipates venous compressive crises.Strabismus arises when inflamed rectus muscles, swollen by hydrated glycosaminoglycans, lose contractility and compliance. The incomitance is moderated by increasing stiffness affecting all the rectus muscles, as they are stretched during cone expansion.Immunomodulation, which rapidly reduces cone volume, relieving muscle elongation and stiffness, may paradoxically unmask strabismus. However, ciclosporin A suppresses late post-inflammatory fibrosis and only 4 of 71 patients so-treated required strabismus surgery.The cone model also accounts for the variety of clinical presentations of thyroid eye disease.
甲状腺眼病的临床特征取决于眼眶的分区；特别是肌圆锥，它由直肌、肌间隔和后巩膜限定。圆锥体附着在眼眶顶点，包含后眼球、肌肉腹、脂肪垫以及血液循环、视神经和 CSF 鞘。它被可移动的眶隔外脂肪包围。甲状腺眼病是由于圆锥内的肌肉腹和脂肪扩张引起的。圆锥体的力学特性决定了疾病分为三个阶段：周向扩张，眶隔外脂肪向前移位；轴向伸长，圆锥体压力增加；后静脉流出阻抗，圆锥体水肿和静脉血流逆转。静脉血流逆转可在结膜循环中观察到。它最初是短暂的，伴随着眼球运动引起的圆锥体压力升高，但后来成为永久性的。它是一个有用的临床体征，可以定位患病的肌肉，并预测静脉压迫危象。当发炎的直肌因水合糖胺聚糖而肿胀，失去收缩性和顺应性时，就会出现斜视。随着圆锥体扩张时所有直肌的拉伸，斜视的程度会因影响所有直肌的刚性增加而得到缓解。免疫调节可迅速缩小圆锥体体积，缓解肌肉伸长和僵硬，尽管这可能会使斜视“暴露”出来。然而，环孢素 A 抑制晚期炎症后纤维化，只有 71 名接受治疗的患者中的 4 名需要斜视手术。圆锥体模型也解释了甲状腺眼病的各种临床表现。
