Thyroid eye disease is not just about the thyroid. It is an autoimmune condition that attacks the tissues around the eye, and it can move fast when it is active. Knowing what phase you are in changes everything about how it is managed.

Thyroid eye disease (TED), also called Graves’ ophthalmopathy or thyroid-associated orbitopathy, is an autoimmune condition in which the immune system attacks the soft tissues and muscles inside the orbit, the bony socket that contains the eye. The muscles swell, the fatty tissue behind the eye expands, and the eye is pushed forward. This protrusion, called proptosis (also seen in orbital cellulitis) or exophthalmos, is the most visible sign of the condition but not the only one. The eyelids retract, the surface of the eye is exposed and uncomfortable, double vision can develop, and in severe cases the optic nerve is compressed at the back of the orbit. TED is most commonly associated with Graves’ disease, an autoimmune cause of an overactive thyroid, but it can occur with any thyroid status and occasionally with no thyroid disease at all.

What You Need to Know About TED

TED has two phases: an active inflammatory phase where the disease is progressing and treatment can modify it, and an inactive stable phase where inflammation has burned out but structural changes remain
The active phase typically lasts 12 to 18 months. Identifying it early allows treatment to be timed correctly
Smoking dramatically worsens TED and dramatically cuts the response to treatment. Stopping is the most important thing a patient can do
Thyroid status needs to be stable: both hyperthyroidism and hypothyroidism worsen TED
Severe sight-threatening TED with optic nerve compression requires urgent high-dose steroids or orbital decompression surgery
Most patients with mild to moderate TED improve over time with supportive care and monitoring

Smoking impact 7x Higher risk of developing TED in smokers with Graves’ disease

Active phase 12-18 mo Typical duration of the active inflammatory phase

Severe TED 3-5% Of TED cases develop sight-threatening disease

What TED Does to the Eye and Orbit

Medical illustration showing the clinical signs of thyroid eye disease including proptosis with forward protrusion of the globe, upper eyelid retraction showing sclera above the iris, periorbital swelling, and conjunctival redness — The main clinical signs of TED: proptosis, eyelid retraction, periorbital swelling, and conjunctival injection.

The immune system produces antibodies against a receptor called TSHR (thyroid stimulating hormone receptor) that is expressed both in the thyroid and in the orbital fibroblasts, the connective tissue cells inside the orbit. When these orbital fibroblasts are attacked, they produce large amounts of hyaluronic acid and differentiate into fat cells, dramatically increasing the volume of soft tissue within the rigid bony orbit. The eyeball has nowhere to go except forward. This is proptosis.

The extraocular muscles also swell and become infiltrated with inflammatory cells. They lose their elasticity. Eye movement becomes restricted and painful, and when the two eyes move at different rates, double vision results. The lower rectus muscle is most commonly affected, causing limited upward gaze, though any muscle can be involved. In severe cases, the swollen muscles at the back of the orbit compress the optic nerve as it enters the optic canal, threatening vision.

Active vs Inactive Phase

Side-by-side illustration comparing the active phase of thyroid eye disease on the left with red swollen inflamed periorbital tissues and prominent proptosis, versus the inactive stable phase on the right with settled less swollen appearance and a timeline arrow beneath — Left: active phase with inflammation and swelling. Right: inactive phase, structurally changed but settled. Treatment strategy differs completely between the two.

This is the most important concept in TED management. Everything else flows from it. The clinical activity score (CAS) is assessed at every visit, scoring signs of active inflammation: spontaneous eye pain, pain on eye movement, redness of the eyelids, conjunctival redness, chemosis, swelling of the caruncle, and increasing proptosis. A CAS of 3 or more out of 7 suggests active disease.

During the active phase, the disease is still progressing and the orbital tissues are responding to inflammation. Immunosuppressive treatments work during this window. Waiting too long to intervene means the inflammatory phase burns out with maximal structural damage that becomes fixed. During the inactive phase, rehabilitation surgery can address the residual proptosis, double vision, and eyelid changes, but it cannot reverse the orbital changes that accumulated while the disease was active.

Symptoms

TED presents differently depending on how severe and how active it is. The earliest symptoms are regularly dismissed as tiredness or allergies: grittiness, watering, light sensitivity, pressure behind the eyes. Many patients are told it’s stress. It isn’t. As the condition progresses:

Proptosis: the eye or eyes appear more prominent, the white of the eye becomes visible above and below the iris
Eyelid retraction: the upper eyelid pulls back, giving the eyes a wide, staring appearance
Periorbital swelling: puffiness of the eyelids and around the eyes, often worse in the morning
Double vision: typically on upward or sideward gaze initially, due to restricted inferior rectus
Ocular surface symptoms: dryness, grittiness, and discomfort from corneal exposure due to inadequate eyelid closure
In severe cases: reduced visual acuity, loss of color vision, or a relative afferent pupillary defect suggesting optic nerve compression

Diagnosis and Monitoring

TED is diagnosed clinically in the context of known thyroid disease, supported by thyroid function tests, TSH receptor antibody levels (TRAb), and orbital imaging. An MRI or CT of the orbits confirms proptosis, shows the degree of muscle enlargement, and crucially assesses the space between the swollen muscles at the orbital apex near the optic nerve. A tight orbital apex on imaging in a patient with visual symptoms means decompression is needed urgently. This is not a situation to watch and wait on.

Hertel exophthalmometry measures the degree of proptosis at each visit, providing an objective record of whether the condition is worsening or improving. Visual field testing and OCT of the optic nerve are performed to monitor for early signs of compressive optic neuropathy before it becomes clinically apparent.

Treatment

Selenium and supportive care for mild TED

For mild TED in the active phase, selenium supplementation (200 mcg daily for six months) has been shown in a randomised controlled trial to reduce disease activity and improve quality of life compared to placebo. It is inexpensive, well tolerated, and recommended in European guidelines for mild active TED. Alongside selenium, lubricating eye drops for surface dryness, taping the eyelids at night to protect the cornea, and prism glasses for small-angle double vision all help manage symptoms while the active phase runs its course.

Intravenous steroids for moderate-to-severe active TED

High-dose intravenous methylprednisolone is the first-line treatment for moderate-to-severe active TED. Given as weekly infusions over 12 weeks, it reduces orbital inflammation and can produce meaningful improvement in proptosis, double vision, and soft tissue signs. Response is better the earlier in the active phase treatment is started. Oral steroids are less effective and have a worse side effect profile for the same degree of immunosuppression.

Teprotumumab

Teprotumumab (Tepezza) is a monoclonal antibody that blocks the IGF-1 receptor, reducing the proliferation of orbital fibroblasts that drives the disease. It has transformed outcomes for active moderate-to-severe TED in clinical trials, producing substantial reductions in proptosis and clinical activity that exceed what was achievable with steroids alone. Currently approved in the US and increasingly available elsewhere. Given as eight intravenous infusions over 24 weeks. Side effects include hearing changes in some patients, which requires monitoring.

Orbital radiotherapy

Low-dose radiotherapy to the orbit can suppress orbital inflammation and is used in combination with steroids for moderate-to-severe active TED. Most effective for soft tissue inflammation and double vision. Not recommended in patients with diabetic retinopathy due to radiation sensitivity of already compromised retinal vessels.

Rehabilitation surgery in the inactive phase

Once TED has been inactive for at least six months, surgical rehabilitation can address the residual structural damage. The sequence matters: orbital decompression first (to reduce proptosis), then squint surgery (once the orbit is stable), then eyelid surgery (once eye alignment is corrected). Operating out of sequence leads to unpredictable results. Patients who have surgery before the active phase has fully settled risk exacerbating the disease and invalidating the surgical result.

Thyroid Control and TED: An Underappreciated Connection

Many patients assume that once the thyroid has been treated, the eye disease will follow. It doesn’t work that way. TED has its own trajectory, driven by orbital autoimmunity, and it continues to progress independently of thyroid hormone levels once established. Controlling the thyroid is necessary but not sufficient.

Radioiodine treatment for hyperthyroidism carries a specific risk: it can trigger or worsen TED, particularly in smokers or those with active or severe eye disease at the time of treatment. European guidelines recommend prophylactic steroids during radioiodine treatment for patients with any degree of TED. This is something to discuss explicitly with both the endocrinologist and ophthalmologist from the oculoplastics and orbit team before radioiodine is administered.

Hypothyroidism after thyroid treatment is equally important to avoid: undertreated hypothyroidism worsens TED just as hyperthyroidism does. The target is euthyroidism, normal stable thyroid function, throughout the management of TED.

Seek Urgent Review If You Notice

Sudden reduction in vision or color vision in one or both eyes
New pain behind the eyes at rest, not just on movement
Rapid worsening of proptosis over days rather than weeks
An eye that cannot close fully, particularly at night, causing corneal exposure
Any change in the appearance of the optic nerve on OCT or visual field defect at a monitoring visit

Sight-threatening TED from optic nerve compression or severe corneal exposure is rare but moves quickly when it happens. Compressive optic neuropathy can cause permanent visual loss within days if not treated with high-dose steroids or emergency orbital decompression. Any reduction in vision in a patient with TED is an urgent ophthalmology review the same day, not a waiting list referral.

Frequently Asked Questions About Thyroid Eye Disease

My thyroid levels are normal now. Why are my eyes still getting worse?
Because the two run on separate tracks. TED and thyroid hormone levels follow separate timelines once the orbital autoimmune process has started. The orbital inflammation is driven by antibodies and immune cells that continue operating independently of what is happening in the thyroid gland itself. Getting the thyroid to normal is important, but it does not switch off the orbital disease. The eye disease runs its own course over 12 to 18 months, regardless of thyroid status.
Will my eyes ever look normal again?
Possibly. The swelling and redness of the active phase do resolve once inflammation burns out. But the structural changes that accumulate during the active phase, particularly proptosis and eyelid retraction, often persist into the inactive phase and require surgical rehabilitation to correct. How much change remains depends on how severe the active phase was and how quickly it was treated. The realistic expectation after TED is not necessarily a return to exactly how you looked before, but in most cases a significant improvement is achievable.
Do I have to stop smoking?
Bluntly: yes. Smoking is the single most modifiable risk factor for TED. Smokers with Graves’ disease have a seven times higher risk of developing significant TED than non-smokers. Smoking also reduces the response to treatment: patients who continue smoking during immunosuppressive therapy have measurably worse outcomes. If there is one thing an ophthalmologist will be categorical about in TED, it is this.
How long will I have double vision?
Double vision in TED is caused by restricted, fibrotic extraocular muscles. During the active phase it fluctuates and changes. Once the disease is inactive and stable for at least six months, squint surgery can straighten the eyes and restore single vision in most patients. Prism glasses help manage double vision while waiting for surgery. Most patients with TED-related strabismus achieve single vision in the primary position (straight ahead) after surgery, though gaze in extreme positions may remain diplopic.
What is orbital decompression and will I need it?
Orbital decompression removes one or more walls of the bony orbit to give the swollen orbital contents more space, reducing proptosis and relieving any optic nerve compression. It is needed urgently when the optic nerve is threatened, and electively in the inactive phase to reduce residual proptosis for cosmetic and functional reasons. Not everyone with TED needs it: most mild to moderate cases don’t. But for patients with significant proptosis after the active phase, decompression is often the most impactful single procedure in the rehabilitation sequence.
Can TED come back after it has settled?
Recurrence of active TED is uncommon but not impossible, particularly if thyroid status becomes unstable again or if the patient resumes smoking. The risk of recurrence is lower in patients who achieve sustained euthyroidism and remain non-smokers. Patients who have had TED should have their thyroid function monitored regularly, indefinitely. Fluctuations in thyroid status are the most common trigger for reactivation, and catching them early matters.

If you would like to learn more, the American Academy of Ophthalmology’s Graves’ disease page and the American Thyroid Association’s thyroid eye disease page offer additional patient-friendly information about the condition and its treatment.

Thyroid eye disease (TED), also called Graves’ orbitopathy (GO), is an autoimmune orbital inflammatory condition driven by shared autoantigens , primarily the thyrotropin receptor (TSH-R) and insulin-like growth factor-1 receptor (IGF-1R) , between the thyroid gland and orbital fibroblasts. It affects approximately 25-50% of patients with Graves’ hyperthyroidism to some degree, and is the most common cause of both unilateral and bilateral proptosis in adults. TED runs a biphasic course: an active inflammatory phase of variable duration (typically 6-24 months) followed by an inactive fibrotic phase. Management decisions are time-sensitive , interventional treatment is most effective during the active phase. Mild disease is managed conservatively; moderate-to-severe or sight-threatening disease requires immunosuppression, and in some cases, teprotumumab (an IGF-1R inhibitor) or orbital surgery. Smoking is the single most modifiable risk factor, doubling TED risk and worsening its severity.

Clinical Overview: Thyroid Eye Disease

Classification (EUGOGO): Mild TED: minor eyelid signs, soft tissue involvement, proptosis up to 3 mm above normal; no corneal or optic nerve involvement; no significant quality-of-life impact. Moderate-to-severe TED: significant proptosis (>3 mm above normal), diplopia, soft tissue involvement, corneal exposure , not immediately sight-threatening but substantially affects function. Sight-threatening TED: dysthyroid optic neuropathy (DON) or corneal breakdown from exposure keratopathy.
CAS (Clinical Activity Score): 7-point score assessing active inflammation: spontaneous orbital pain (1), pain on eye movement (1), eyelid erythema (1), eyelid edema (1), conjunctival injection (1), chemosis (1), caruncle/plica inflammation (1). Score ≥3/7 = active disease. CAS drives treatment , immunosuppression works only in active disease.
Thyroid status: Control of thyroid function is the single most important systemic intervention. Persistent hyperthyroidism (TSH-stimulating antibody [TRAb] drive) worsens TED. Radioiodine (RAI) can transiently worsen TED , cover with oral prednisolone if RAI is used in a patient with active TED. Thyroidectomy or anti-thyroid drugs (carbimazole, propylthiouracil) are preferred over RAI in moderate-to-severe active TED.
Moderate-to-severe active TED: IV methylprednisolone (IVMP) 500 mg weekly × 6 weeks, then 250 mg weekly × 6 weeks (EUGOGO-recommended protocol). Response rate approximately 75-80%. Oral steroids are less effective and have more systemic side effects. Selenium 200 µg/day for 6 months reduces progression in mild active TED (EUGOGO RCT).
Teprotumumab (Tepezza): IGF-1R monoclonal antibody. OPTIC trial: 83% responder rate vs 10% placebo for proptosis reduction ≥2 mm. Approved in USA; not yet widely available in UK/EU. Very high cost. Also reduces CAS, diplopia, and soft tissue signs. Hyperglycemia and hearing loss are key adverse effects.
Rehabilitative surgery sequence: Orbital decompression → squint surgery → eyelid surgery. Always in this order , earlier steps alter the later ones. Decompression changes ocular motility; squint surgery changes eyelid position.

TED in Graves’ disease 25-50% Of Graves’ hyperthyroidism patients have clinically apparent TED

Smoking multiplier ×7-8 Risk of severe TED in smokers vs non-smokers with Graves’

IVMP response rate ~75% Of moderate-to-severe active TED responds to IV methylprednisolone

Pathophysiology

TED results from autoimmune activation of orbital fibroblasts expressing TSH-R and IGF-1R on their surface. T-lymphocytes and B-lymphocytes sensitized to these receptors infiltrate the orbital connective tissue and trigger fibroblast differentiation into adipocytes (expanding orbital fat volume) and myofibroblasts (producing glycosaminoglycans , particularly hyaluronic acid , in the extraocular muscles). Both processes expand orbital volume. Because orbital volume is constrained by the bony walls and orbital septum, volume increase displaces the globe forward (proptosis) and compresses structures at the orbital apex.

Dysthyroid optic neuropathy (DON): The most serious complication. Enlarged extraocular muscles at the orbital apex compress the optic nerve, reducing blood supply and causing progressive visual field loss, reduced color vision, and afferent pupillary defect (RAPD). DON may occur without severe proptosis , muscle apical crowding can compress the optic nerve in an eye that is not dramatically proptotic. Fundoscopy may be normal (compressive neuropathy, not atrophy, early on). Color vision testing and RAPD assessment at every TED visit is non-negotiable.

Relationship to thyroid status: TRAb (TSH receptor antibody) titre correlates with TED activity and severity. TRAb measurement at diagnosis and at 6-12 monthly intervals tracks disease trajectory. A rising TRAb titre in a patient with inactive TED is a warning sign of reactivation. Euthyroid TED (TED without clinical hyperthyroidism) occurs in approximately 5-10% of cases; these patients have Graves’ autoimmunity without overt thyroid dysfunction.

Assessment and Staging

Exophthalmometry: Hertel exophthalmometer measures proptosis bilaterally at a fixed base distance. Normal values: 14-21 mm (varies by ethnicity and gender; East Asian populations have lower normal ranges). Asymmetry greater than 2 mm is significant. Document both absolute values and change from baseline. Proptosis above 25 mm or asymmetry above 5 mm warrants CT orbit.

Ocular motility: Inferior and medial rectus are the most commonly affected muscles (earliest and most severely involved). Fibrosis produces restrictive strabismus , limitation of upgaze (inferior rectus) and abduction (medial rectus). Hess chart documents motility defect. Prism cover test quantifies the deviation. Diplopia in TED should be assessed with the Parks-Bielschowsky three-step test to confirm restrictive rather than paretic pattern.

CT/MRI orbit: CT: best for bony orbital anatomy, decompression planning, and optic nerve canal width. Shows “Coca-Cola bottle” sign (muscle belly enlargement with tendon sparing , pathognomonic for TED, distinguishing it from orbital myositis which involves the tendon). MRI: better for soft tissue detail, active inflammation assessment (high T2 signal in muscles = active disease), and superior visualization of orbital apex crowding.

Color vision and RAPD: Ishihara plates and Farnsworth-Munsell testing at each visit. Any new color defect or RAPD is DON until proven otherwise. Humphrey visual field testing: cecocentral scotoma, enlarged blind spot, or inferonasal depression in DON. OCT of the optic nerve head: RNFL thinning develops later in DON , a normal RNFL does not exclude active compression.

Management: Active Phase

IV methylprednisolone (IVMP): EUGOGO protocol for moderate-to-severe active TED: 500 mg IV weekly for 6 weeks, then 250 mg IV weekly for 6 weeks (total 4.5 g cumulative dose). Exceeding 8 g cumulative dose carries significant risk of acute liver failure , stay within the guideline dose. Monitor liver function before and during treatment. Contraindications: hepatitis B/C, active liver disease, recent acute cardiac event, uncontrolled hypertension, severe diabetes.

Orbital radiotherapy: 20 Gy in 10 fractions to the orbital apex and retrobulbar tissues. Most effective for improving ocular motility (reduces muscle fibrosis). Modest benefit for soft tissue signs, less for proptosis. Combined IVMP + radiotherapy shows superior results to either alone for motility (CRIPES trial). Contraindicated in: diabetes (risk of radiation retinopathy), under 35 years (lifetime radiation risk), active retinal vascular disease.

Teprotumumab: Infusion every 3 weeks for 8 doses. Significant benefit: proptosis reduction median 2.8 mm vs 0.5 mm placebo (OPTIC trial); also reduces CAS, diplopia, and lid retraction. Current access: approved in USA (2020); compassionate use in UK/EU; high cost (approximately $300,000 per treatment course). Monitoring: blood glucose (hyperglycemia in ~10%), audiogram (sensorineural hearing loss in ~10%), IBD exacerbation risk.

Management: Sight-Threatening TED

Dysthyroid optic neuropathy (DON) , emergency: High-dose IV methylprednisolone 1 g daily for 3 days. If no response within 2 weeks: urgent orbital decompression surgery. Decompression removes one or more orbital walls (typically medial wall and floor) to expand the bony orbit and relieve apical crowding. If DON continues to worsen despite IVMP: proceed to decompression urgently. Do not wait for a full 6-week IVMP course if vision is deteriorating.

Exposure keratopathy: Inadequate eyelid closure from proptosis and lid retraction causes corneal desiccation. Management: intensive lubricants, moisture chambers at night, taping the eyelid closed during sleep. Botulinum toxin injection into the levator muscle produces temporary ptosis and corneal protection. Urgent surgical tarsorrhaphy (permanent or temporary) if corneal ulceration develops.

Rehabilitative Surgery

Orbital decompression: Indicated for: DON not responding to steroids, severe proptosis causing exposure keratopathy, disfiguring proptosis in inactive disease, pre-decompression before squint or lid surgery. Approach: balanced decompression (medial wall + floor) most common; fat decompression alone for mild proptosis. Postoperative diplopia may worsen in 10-20% of cases , inform patients.

Strabismus surgery: Once disease inactive for at least 6 months and orbit stable. Adjustable sutures preferred , TED muscle responses are unpredictable. Aim for single binocular vision in primary position and reading position; full motility restoration is rarely achievable. Multiple procedures may be required.

Eyelid surgery: Last in the sequence. Upper lid lowering (lid retraction repair via Müller’s muscle recession), lower lid raising (spacer graft), blepharoplasty for fat excess. Timing: at least 6 months post-decompression, after orbit is stable.

Clinical Decision Points

New Graves’ diagnosis, TED not yet apparent: Baseline exophthalmometry, Hertel reading, color vision, and orthoptic assessment at diagnosis. Smoking cessation counseling. Avoid RAI if any orbital signs are present , use carbimazole or thyroidectomy instead.
Mild TED, CAS 2/7: Selenium 200 µg/day, lubricants, UV-protective glasses, smoking cessation. No immunosuppression. Review at 3 months , CAS may rise.
Moderate-to-severe active TED, CAS 4/7: IVMP 500 mg/250 mg protocol. Consider adding orbital radiotherapy for motility involvement. Refer to combined TED clinic (endocrinology + ophthalmology).
Diplopia in inactive TED: Prism glasses for small, stable deviations. Plan strabismus surgery once orbit stable for 6 months. Do not operate during active phase.
Reduced color vision or new RAPD in TED patient: DON until proven otherwise. IVMP 1 g daily × 3 days immediately. Urgent imaging. If no response at 2 weeks: orbital decompression.

Same-Day Assessment Required

Any TED patient reporting reduced vision, new color desaturation, or change in visual field , DON; needs same-day color vision, RAPD, VF assessment and urgent imaging
Corneal ulcer from exposure keratopathy in TED , emergency corneal management plus tarsorrhaphy consideration
Acute orbital hemorrhage post-decompression (rare) , vision-threatening compartment syndrome; orbital massage and urgent decompression if needed

DON may present subtly , a patient who reports only that colors look “washed out” or that their vision is slightly duller than usual in one eye is describing early optic nerve compression. Any unexplained visual change in a known TED patient, however mild it seems, requires same-day assessment of color vision and RAPD before assuming it is refractive or due to corneal surface changes.

Clinical Pearls: Thyroid Eye Disease

DON can occur without severe proptosis. The eye that does not look dramatic is the one you miss.
The classic teaching is that severe proptosis indicates severe TED. But DON from apical muscle crowding can occur in a relatively non-proptotic eye where enlarged rectus muscles fill the orbital apex without forward displacement of the globe. A patient with “mild” clinical TED who reports subtle color change should have color vision tested immediately. The absence of dramatic proptosis does not exclude sight-threatening apical crowding , CT orbit is required whenever DON is suspected regardless of the external appearance.
The surgical sequence is non-negotiable: decompression first, then squint, then lids. Reversing it causes preventable harm.
Orbital decompression changes the globe position, which changes the strabismus. Squint surgery changes the eyelid position. Performing lid surgery before addressing the strabismus, or squint surgery before a necessary decompression, means reoperation and additional scarring. Every TED patient planning rehabilitative surgery should be managed by a combined oculoplastics and orthoptic team who understands and follows this sequence. Patients often push for lid surgery first because it is the most cosmetically visible change , this pressure must be resisted.
Euthyroid TED is not rare. Check TRAb even when thyroid function tests are normal.
Approximately 5-10% of TED patients are euthyroid at presentation. The diagnosis of TED can be made on clinical grounds (proptosis, lid retraction, restrictive myopathy) and confirmed by TRAb positivity , without any thyroid function abnormality. These patients are still managed with the same EUGOGO classification and treatment approach. Missing TED because “the thyroid function is normal” is a preventable diagnostic error. TRAb is the most sensitive serological marker and should be checked in any patient with suspected orbital disease, regardless of TSH.

Further reading: EUGOGO Clinical Guidelines for TED. Related conditions: orbital cellulitis (differential for acute proptosis), uveitis (anterior segment TED overlap). Subspecialty context: oculoplastics and orbit subspecialty page.