Along its path it can become compressed, inflamed, ischaemic or mechanically stretched by the abnormally enlarged surrounding extraocular muscles and orbital tissues leading to dysthyroid
optic neuropathy (DON).
Two of the six patients had dysthyroid optic neuropathy; one proved refractory to intravenous methylprednisolone and the other worsened despite orbital decompression surgery.
One patient with dysthyroid optic neuropathy experienced an almost immediate, significant improvement in visual acuity; within 10 days of the first infusion, this patient's vision went from perception of light only to 6/18, a metric rating that corresponds to 20/60 on the visual acuity scale.
The other patient with dysthyroid optic neuropathy did not experience any improvement in visual acuity within 12 days of her first infusion, and so opted for an emergency orbital decompression.
A wide variety of problems can cause damage in these areas, including compressions due to arterial-venous malformations (carotid artery aneurysm, cavernous sinus thrombosis or fistula), tumours (pituitary adenoma, naso-pharyngeal carcinoma, meningioma, metastases), and inflammatory disorders (orbital cellulitis, dysthyroid
eye disease, non-specific granulomatous masses associated with Tolosa-Hunt syndrome).
Examples include entrapment of an EOM due to a blow out fracture, dysthyroid eye disease and ocular myositis.
Associated with systemic thyroid dysfunction, dysthyroid eye disease occurs in patients who are hyperthyroid, hypothyroid or euthyroid.
Dysthyroid eye disease with signs of corneal involvement