Thyroid Eye Disease: Symptoms, Steroids, and Biologics Explained

Thyroid Eye Disease (TED) isn’t just about dry eyes or puffiness. It’s an autoimmune condition that attacks the tissue behind your eyes, causing swelling, pain, and sometimes permanent vision changes. If you’ve been diagnosed with Graves’ disease-or even if your thyroid levels are normal-you could still be at risk. About half of all Graves’ patients develop TED, and it can strike even when thyroid function is stable. The good news? Treatment has changed dramatically in the last five years. No longer is it just about waiting for inflammation to burn out and then fixing the damage with surgery. Now, we have drugs that target the root cause.

What Are the Real Symptoms of Thyroid Eye Disease?

People often mistake TED for allergies or tired eyes. But the signs are more specific. A gritty, sandy feeling in the eyes? That’s common-reported by nearly 8 out of 10 patients. Light sensitivity, redness, and pain when moving your eyes are also red flags. About one in three people notice their eyes bulging forward, a condition called proptosis. Double vision happens in nearly 3 out of 10 cases, especially when looking up or to the side. Eyelids may swell or retract, making it hard to close your eyes fully. And yes, you might cry more than usual-even though your eyes feel dry.

These symptoms usually hit both eyes, but in about 1 in 10 cases, only one eye is affected. The severity is measured using something called the Clinical Activity Score (CAS). If your score is 3 or higher, your disease is still active and inflamed. That’s the window when treatment works best. If you wait too long, the inflammation turns to scar tissue, and the damage becomes permanent. That’s when surgeries for eye alignment or orbital decompression become necessary-and even then, they can’t undo everything.

Why Steroids Are Still the First Line of Defense

For moderate-to-severe TED, intravenous (IV) steroids are still the go-to treatment. The most common is methylprednisolone, given in high doses once a week. A typical course is six weeks of 500 mg, then six weeks of 250 mg. This approach works for 60 to 70% of people. It reduces swelling, eases pain, and can even improve double vision. Many patients notice a difference within two weeks.

But IV steroids aren’t perfect. Side effects are real. Weight gain is common-on average, people gain over 8 kilograms. Blood sugar spikes, leading to prediabetes in about 1 in 5 patients. Bone density drops, raising the risk of fractures. That’s why doctors limit the total dose to no more than 5 grams over the course of treatment. Too much can damage the liver.

Oral steroids like prednisone are easier to take, but they’re less effective and cause more side effects. About a quarter of people relapse after stopping them. That’s why IV steroids are preferred for serious cases. Still, for mild TED, doctors often skip steroids altogether and recommend artificial tears, selenium supplements, and quitting smoking.

Biologics: The Game-Changer in TED Treatment

In 2020, the FDA approved teprotumumab (brand name Tepezza®), the first drug designed specifically to treat TED at its source. Unlike steroids, which broadly suppress the immune system, teprotumumab targets the insulin-like growth factor-1 receptor (IGF-1R)-the exact protein that triggers inflammation in the eye tissues. This is a breakthrough. It’s not just masking symptoms. It’s stopping the disease from eating away at your eye structure.

The results are striking. In the OPTIC clinical trial, 71% of patients saw their eyes recede by at least 2 millimeters after eight infusions. Only 20% of those on placebo did. Double vision improved in nearly 6 out of 10 patients on teprotumumab, compared to 1 in 4 on placebo. Many people who couldn’t drive or read due to double vision regained normal vision.

The treatment is given as eight infusions over 22 weeks. Each dose starts at 10 mg/kg, then increases to 20 mg/kg. The cost? Around $360,000 in the U.S. Insurance often covers it, but getting approval can take 47 days on average. Some patients report being denied coverage outright-especially if they’re on Medicaid.

Side effects aren’t minor. Muscle spasms affect about 1 in 4 people. About 1 in 10 report hearing changes-muffled sounds or ringing. Blood sugar rises in 8% of cases. The FDA added a boxed warning for these risks in 2021. But for many, the trade-off is worth it. Patient surveys show 74% satisfaction with biologics, compared to just 58% with steroids.

What About Other Biologics?

Teprotumumab isn’t the only option on the horizon. Satralizumab (Enspryng®), approved in 2023, is a subcutaneous injection that blocks IL-6, another key player in TED inflammation. Early data shows it reduces proptosis in over half of patients. It’s easier to administer than infusions, and might be cheaper long-term.

Rituximab and tocilizumab have been used off-label for years, but the evidence is weaker. They’re sometimes tried when teprotumumab fails or isn’t available. But they’re not FDA-approved for TED, and insurance rarely covers them for this use.

A biosimilar version of teprotumumab is expected by 2025. If it cuts costs by 30-40%, access will improve dramatically. Right now, only 45% of ophthalmologists routinely use biologics. In rural areas, that number drops to 28%. Cost and access are still the biggest barriers.

What You Can Do Right Now

If you’re diagnosed with TED, timing matters. The first six months are the most critical. If you’re still in the active phase-meaning your eyes are red, swollen, or painful-talk to your doctor about starting treatment now. Don’t wait for it to get worse.

Quit smoking. Seriously. Smokers are nearly eight times more likely to develop severe TED. Smoking also makes steroids and biologics less effective. If you’re on radioactive iodine for Graves’ disease, ask about taking steroids at the same time. It cuts your TED risk in half.

For mild cases, preservative-free artificial tears help. Selenium supplements (200 mcg daily) have been shown to improve quality of life slightly. Prisms in glasses can fix double vision if the misalignment is small. But if your eye muscles are too stiff or swollen, prisms won’t help-and surgery might be the only option later.

When Surgery Becomes Necessary

Surgery is not a first step. It’s a last resort, done only after the disease has gone inactive-usually after 6 to 24 months of no change. There are three main types: orbital decompression (to reduce bulging), strabismus surgery (to fix double vision), and eyelid surgery (to correct retraction).

Decompression can reduce proptosis by 2 to 5 millimeters. But it carries risks: 15% of patients develop new or worse double vision. Sinus infections happen in 8%. Vision loss is rare-under 1%-but it’s real.

Many people avoid surgery by using biologics early. That’s why experts now say: treat inflammation fast, not just fix the damage later.

What’s Coming Next?

Research is moving fast. The TOPAZ trial is testing whether adding selenium to teprotumumab improves results. Early data shows an 82% response rate-higher than either treatment alone. Scientists are also looking at genetic markers that predict who will get TED and who will respond best to which drug. Within five years, we may be able to test a blood sample and know exactly which treatment will work for you.

For now, the message is clear: TED is not something you have to live with. It’s treatable. But only if you act early. If you’re experiencing eye symptoms along with thyroid issues, don’t wait. See an endocrinologist and an ophthalmologist who specializes in TED. The tools to protect your vision are here. You just need to ask for them.