OVERVIEW
Thyroid-associated ophthalmopathy (TAO) is one of the most common orbital diseases in adults, often with bilateral onset and a tendency for some patients to resolve spontaneously.Patients with TAO may have hyper-, hypo-, or normal thyroid function.TAO can be divided into two types: type I, which is characterized by a predominantly retrobulbar adipose and connective tissue infiltrate, and type II, which is characterized by an exophthalmic myositis. These two types may coexist or occur separately.
Etiology
The exact pathogenesis of TAO is unknown, and it is generally considered to be an autoimmune or organ-immune disease.The pathohistological features of TAO are early inflammatory cell infiltration and edema, and late tissue degeneration and fibrosis.
Symptoms
1. Ocular manifestations
(1) Eyelid sign It is an important sign of TAO, which mainly includes swelling of the eyes and face, eyelid retraction (Dalrymple’s sign), delayed fall of the upper eyelid (vonGraefe’s sign), and reduction of transient reflexes, among which eyelid retraction and delayed fall of the upper eyelid are the characteristic manifestations.
(2) Eyeball protrusion Mostly axial eyeball protrusion.
(3) Diplopia and ocular motility disorders TAO can cause multiple extraocular muscles to be involved, resulting in ocular motility disorders and diplopia. Involvement of the inferior rectus, superior rectus and internal rectus muscles is common, while the involvement of the external rectus muscle is less common. In the advanced stage of the disease, due to the fibrosis of extraocular muscles, the eyeball can be fixed in a certain position.
(4) Conjunctival and corneal lesions The conjunctiva is congested and edematous, and exposure keratitis and corneal ulcers may occur in the cornea.
(5) Retinopathy and optic neuropathy Compression of the orbital tissue by edema can lead to compressive retinopathy and optic neuropathy. Patients may have reduced visual acuity and visual field defects; oedema or pallor of the optic disk, tortuous dilatation of retinal veins, retinal edema and exudation can be seen in the fundus.
2. Systemic manifestations
It may be accompanied by clinical manifestations of thyroid function changes.
Examination
1. Routine eye examination
Including visual acuity, intraocular pressure, eye protrusion and eye movement.
2. CT scan
The extraocular muscles of TAO patients can be seen to be hypertrophied, and the lesion mainly involves the muscle belly. In severe cases, it can lead to optic nerve compression in the orbital aponeurosis area, resulting in significant vision loss or loss of vision.
3.MRI scan
MRI scan can show the morphology of extraocular muscles and other soft tissues in the orbit more clearly than CT scan. According to the signal changes of extraocular muscles, it can help to determine the changes of the disease and guide the treatment. If the extraocular muscles show long T1 and slightly long T2 signals, it suggests that the muscles are in the inflammatory edema stage, and the treatment effect is more obvious; if it shows long T1 and short T2 signals, it suggests that the muscle fibrosis is more serious, and the treatment effect is poorer.
Diagnosis
The diagnosis is made on the basis of typical clinical findings, thyroid hormone levels [T3, T4, and thyroid stimulating hormone (TSH)], and orbital imaging.
Treatment
This includes systemic and ocular therapy. Systemic therapy is aimed at correcting thyroid dysfunction. Ocular therapy is directed at exposure keratitis, compressive optic neuropathy, and severe congestive orbital lesions. Major therapeutic measures include glucocorticoids, immunosuppressive agents, radiation therapy, and surgery. Diplopia can be corrected with a trial of prisms. To prevent the development of exposure keratitis, the lid fissure may be covered at night and lubricating eye drops may be used; lid margin suturing may be performed if necessary. In the acute phase of orbital pathology, orbital decompression is feasible if significant visual impairment occurs; in the stabilized phase of the disease, orbital decompression may be performed to improve proptosis, strabismus correction, and eyelid surgery, depending on cosmetic needs. The general order of choice for surgical procedures is: orbital decompression, extraocular muscle correction surgery, and eyelid surgery.
Questions you may be concerned about
What is the treatment for thyroid-related eye disease?
Thyroid-related eye disease can be treated with antithyroid medication, iodine 131 therapy, etc. For severe protruding eyes with significant threat to vision, orbital decompression surgery is feasible, and consultation with a physician is recommended.
Thyroid-associated ophthalmopathy, or Graves’ ophthalmopathy, is categorized into non-invasive and invasive proptosis depending on the severity of the condition. It is one of the specific manifestations of diffuse goiter with hyperthyroidism.
Non-infiltrative synophthalmos usually does not require special treatment, and the synophthalmos will be relieved with the control of hyperthyroidism. In the treatment of hyperthyroidism, small doses of antithyroid drugs are used to slowly control the symptoms of hyperthyroidism, while timely and appropriate amounts of thyroid preparations can help to improve the symptoms of protruding eyes. The use of radioactive iodine 131 treatment for severe cases of proptosis should be cautious.
People with proptosis should also be careful to avoid smoking, which can aggravate proptosis. Intraorbital decompression surgery may be indicated for severe protruding eyes with significant visual threat.
During the detection of thyroid-related eye disease, it is necessary to eat a proper diet and try not to eat foods containing iodine, otherwise it will lead to an increase in the level of thyroid hormones, which is not conducive to the control of the disease. Thyroid hormone levels should be monitored regularly during the period, and the medication should not be stopped when the levels return to normal, but should be stopped under the guidance of a medical professional.