Thyroid eye disease (TED) is an autoimmune condition that inflames the tissues behind the eyes, causing bulging, double vision and, in severe cases, vision loss. Teprotumumab (Tepezza) transformed treatment after its 2020 approval and now generates more than $1 billion in sales every six months, but it has also been the subject of hearing-loss warnings and a federal product-liability litigation. A second therapy, veligrotug (Lumvoa), was approved in June 2026, opening a new competitive phase.
Core Patient Questions
What is thyroid eye disease?
Thyroid eye disease (TED), also called Graves' orbitopathy or thyroid-associated ophthalmopathy, is an immune-mediated condition in which the tissues around and behind the eyes become inflamed and swollen. A medical review describes it as the most common orbital disorder in adults, predominantly occurring in mid-adulthood and more often in women. It typically occurs in people with autoimmune thyroid disease, especially Graves' disease.
The inflammation enlarges the eye muscles and orbital fat, pushing the eye forward and restricting its movement. TED usually has an active phase of inflammation lasting months to a couple of years, followed by a more stable phase in which scarring and fibrosis can leave lasting changes. Symptoms range from mild irritation to disfigurement, double vision and, rarely, loss of sight. The condition affects appearance, work and quality of life, which is why treatments that reverse bulging have attracted so much attention and investment.
What causes thyroid eye disease?
TED is driven by autoimmunity. Autoantibodies that target the thyrotropin (TSH) receptor, the same receptor involved in Graves' disease, are thought to activate fibroblasts in the orbit. A review states the disease is more common and worse in smokers and is propagated by autoantibodies targeting the thyrotropin receptor. The insulin-like growth factor 1 receptor (IGF-1R) also plays a central role: IGF-1R and the TSH receptor form physical and functional complexes that amplify inflammatory signaling, which is why drugs blocking IGF-1R can reduce bulging.
The resulting orbital inflammation causes muscle and fat expansion and eventually fibrosis. Other risk factors include female sex, age, genetics and thyroid-hormone swings during treatment of hyperthyroidism. Smoking cessation is the single most important modifiable factor, because smokers tend to have more severe disease and respond less well to treatment.
Is thyroid eye disease the same as Graves' disease?
No, although the two are closely linked. Graves' disease is an autoimmune disorder of the thyroid gland that usually causes hyperthyroidism. TED is a separate autoimmune process in the eye socket that most often accompanies Graves' disease. According to Michigan Medicine, about 50 percent of patients with Graves' disease develop eye problems. TED can also occur with Hashimoto's thyroiditis, and it may appear before, at the same time as or after the thyroid diagnosis, sometimes when thyroid hormone levels are normal.
Importantly, treating the thyroid does not automatically cure the eye disease, and thyroid treatments such as radioactive iodine can sometimes worsen it. For that reason people with Graves' disease are usually monitored for eye symptoms and sometimes referred to an ophthalmologist with oculoplastic or orbital expertise. Endocrinologists and eye specialists typically coordinate care.
What are the first signs of thyroid eye disease?
Early signs are often subtle and mistaken for allergies or tired eyes: a gritty or dry feeling, redness, tearing, light sensitivity, puffy or swollen eyelids and pressure or pain behind the eyes. Many patients notice a "staring" look from eyelid retraction, in which the upper lid sits too high. Specialists describing the OPTIC trial list proptosis (bulging), eyelid retraction, strabismus, compressive optic neuropathy and poor quality of life as characteristic features.
Double vision, especially when looking up or sideways, and a change in how glasses fit can follow. Clinicians score inflammation using a Clinical Activity Score (CAS) that counts pain, redness and swelling; trials often enrolled patients with a CAS of at least 4. Because treatment works better early, anyone with Graves' disease and new eye symptoms should seek prompt evaluation rather than waiting for the eyes to bulge.
Why do the eyes bulge in thyroid eye disease?
The eye sits in a bony socket with little room to expand. In TED, inflammation causes the extraocular muscles to swell and the fatty tissue to increase, and the volume of tissue behind the eye rises. Because the socket's bony walls do not give, the eye is pushed forward, a finding known as proptosis. A review describes an orbital inflammatory cascade leading to muscle and fat expansion, in some cases ending in progressive fibrosis.
Orbital fibroblasts, stimulated through the IGF-1R and TSH receptor pathways, produce molecules that attract water and build up fat, adding to the swelling. Eyelid retraction can exaggerate the appearance of bulging. Proptosis is measured in millimeters with an exophthalmometer, and treatment trials use a reduction of 2 millimeters or more as a key benchmark. Surgery can also create more space by decompressing the orbit.
Can thyroid eye disease affect only one eye?
Yes. Although TED usually affects both eyes, severity is often unequal and one eye can be clearly worse than the other, sometimes for months or years. Michigan Medicine's description of the pivotal OPTIC trial notes that proptosis was measured in the more severely affected eye, reflecting that asymmetry. Truly one-sided disease occurs but is less common, and doctors may order imaging to rule out other causes of one-eyed swelling, such as an orbital tumor, infection or vascular malformation.
Even when only one eye seems affected, the second may develop symptoms later, so monitoring continues. The relevance for treatment is that clinical measurements, such as proptosis and double vision, guide therapy eye by eye, and the response is often compared between eyes. Anyone with sudden one-sided bulging, pain or vision change should be evaluated promptly to exclude other conditions.
Can thyroid eye disease cause blindness?
Rarely, but it can threaten sight. The most serious mechanism is compressive optic neuropathy, in which swollen muscles press on the optic nerve; it is among the characteristic complications listed in specialist reviews, and the American Academy of Ophthalmology has described the disease as sight-threatening.
Another risk is corneal damage when the eyelids cannot close fully, which leaves the surface dry and prone to ulceration. Warning signs include dimming or graying of vision, loss of color vision, worsening double vision or severe pain, and they warrant same-day evaluation. Emergency treatment with high-dose intravenous steroids or surgical orbital decompression can preserve vision. Most patients never lose sight, but the risk is the reason clinicians take moderate-to-severe disease seriously and why smoking cessation and early referral are emphasized. Patients should also keep their eyes lubricated and avoid sleeping with the lids open.
How is thyroid eye disease diagnosed?
Diagnosis is clinical, based on symptoms and a specialist eye examination combined with thyroid testing. Clinicians measure proptosis, eyelid position, eye movements, double vision, color vision and optic nerve function, and they assess disease activity with the Clinical Activity Score. Blood tests check thyroid hormones and thyroid autoantibodies, including TSH-receptor antibodies. Imaging with CT or MRI is used when the diagnosis is uncertain, disease is asymmetric or there is concern about optic nerve compression, and it can show enlarged eye muscles.
Because treatment decisions depend on whether disease is active or chronic, staging is crucial; the new generation of therapies has been tested in both. Viridian's veligrotug label includes data from active and chronic TED, whereas earlier trials largely enrolled active, recent-onset disease. Patients should ideally be evaluated by teams that combine endocrinology, ophthalmology and, where needed, oculoplastic surgery.
What treatments are available for thyroid eye disease?
Care starts with supportive measures: stopping smoking, lubricating drops, sunglasses, elevating the head at night and correcting thyroid hormone levels. For active inflammation, intravenous glucocorticoids and, less often, orbital radiotherapy have long been used, and surgery (orbital decompression, strabismus and eyelid procedures) addresses chronic changes. The major advance was teprotumumab (Tepezza), the first IGF-1R inhibitor, approved in January 2020; in the phase 3 OPTIC trial 83% of treated patients versus 10% of placebo patients had a proptosis response at 24 weeks after eight infusions.
On June 26, 2026, the FDA approved veligrotug-vvze (Lumvoa), a five-infusion, 12-week course for TED regardless of disease activity or duration. Other candidates are in development, including a subcutaneous option from Viridian. Choice of therapy depends on disease activity, hearing status, diabetes control, patient preference and insurance coverage, and decisions are best made with a specialist team.
Market and Controversy Questions
Does Tepezza cause permanent hearing loss?
According to the FDA-approved prescribing information, Tepezza may cause severe hearing impairment including hearing loss, which in some cases may be permanent. Patients are advised to have their hearing assessed before, during and after treatment. The European product information reports that events such as deafness, tinnitus, hypoacusis and autophony occurred in 13.8% of patients in clinical trials and post-marketing experience. Not every event is permanent, but the label recognizes that some are, and some patients report lasting hearing loss or tinnitus.
Were patients and physicians adequately warned about the hearing risks associated with Tepezza?
The facts are clear, but the judgment is contested. Tepezza was approved in January 2020 with warnings covering infusion reactions, inflammatory bowel disease flares and hyperglycemia. The FDA approved a supplemental application adding hearing impairment to the Warnings and Precautions section in a letter dated July 17, 2023, about three and a half years later.
Horizon's position was that hearing-related events were consistent with those already described in its label: it said an analysis of eight oncology trials found similar types and incidence of hearing adverse events. Plaintiffs allege that the company knew or should have known of the risk earlier and failed to provide adequate warning; those allegations are unproven. A court will decide whether the original label was adequate.
Why is Tepezza so expensive?
Tepezza is a biologic given as an eight-infusion course, and the cost scales with the patient's weight. Viridian, a competitor, estimates the current list price at roughly $525,000 per complete treatment course for an 80-kilogram patient; this is an internal estimate rather than an Amgen disclosure. Factors behind the price include a small, specialist-driven market of about 2,000 core prescribers by Viridian's estimate and the absence, until mid-2026, of a competing IGF-1R antibody.
The drug was first studied in cancer, where it failed to show efficacy, before being repurposed for TED. Net prices after discounts and rebates are not publicly disclosed, so list-price comparisons should be read with caution. Amgen reported Tepezza sales of $576 million in the second quarter of 2026, which indicates payers are reimbursing the product at scale, with sales for the first half of 2026 up 20% on the prior year.
Does Tepezza's clinical benefit justify its price and potential safety risks?
The efficacy evidence is strong for bulging. In OPTIC, mean proptosis fell 2.82 mm versus 0.54 mm with placebo, and a pooled analysis of three trials found 80.2% of treated patients were proptosis responders versus 14.0% on placebo. Benefits were smaller in smokers, at 70.8%. The Michigan team that developed the drug said the reduction in proptosis lasted at least a year in many patients. Against that stand the hearing warning, hyperglycemia and infusion reactions, plus a six-figure price.
Did the marketing of Tepezza communicate the risk of serious hearing problems?
No regulator has publicly ruled on that question, so the answer rests on allegations. The federal litigation is formally titled In re: Tepezza Marketing, Sales Practices, and Products Liability Litigation, and plaintiffs contend that Horizon promoted the drug as a groundbreaking therapy while withholding information about irreversible hearing damage. Horizon, now part of Amgen, has defended the adequacy of its label, and the company has argued that FDA approval of the label preempts the claims, according to plaintiff-side summaries.
What do the lawsuits concerning Tepezza and alleged hearing damage claim?
Hundreds of patients allege that Tepezza caused permanent hearing loss or tinnitus and that Horizon failed to warn them or their doctors. Cases are consolidated as MDL No. 3079 in the U.S. District Court for the Northern District of Illinois before Judge Thomas Durkin, with Amgen, which acquired Horizon, as defendant. Plaintiff-side trackers put the number at more than 270 pending cases in mid-2026.
One tracker reports that in January 2025 the court denied Horizon's motion to dismiss the failure-to-warn claims in the bellwether cases. Trial dates have shifted repeatedly; a September 2026 tracker says no bellwether trial has occurred, no settlement exists and 2026 trial dates were struck in October 2025. Status changes frequently, so readers should check the court docket.
How big is the thyroid eye disease market, who are the key players and what is the outlook?
Amgen's Tepezza leads. The company reported $490 million in first-quarter 2026 and $576 million in second-quarter sales, about $1.07 billion for the half-year, up 20%. Amgen inherited the drug through its acquisition of Horizon in 2023. Viridian's Lumvoa, approved June 26, 2026 and launched immediately, is the first direct competitor, supported by two phase 3 trials in active and chronic TED. Viridian is also developing a subcutaneous candidate, elegrobart, with phase 3 results expected in 2026.
Amgen attributed part of its first-quarter growth to higher inventory and a higher net selling price, so underlying demand is less clear than the headline. Viridian is targeting a narrow specialist call point and a shorter five-infusion course. Outlook depends on whether competition shortens treatment, whether safety differentiation emerges and how the litigation unfolds. The hearing question is likely to remain a competitive talking point.