Graves' disease and your eyes: what to check at diagnosis, and how radioactive iodine, smoking and thyroid levels can matter

Graves' disease is a condition of the thyroid gland, but the same immune reaction can reach the eyes. Many people hear about tablets, radioactive iodine or surgery, and nobody mentions the eyes until they turn gritty or look different. This piece covers Graves disease eye problems in plain terms: what to watch for, what the guidelines say about radioactive iodine, smoking and thyroid levels, and when to ask for an eye doctor. The choice of thyroid treatment belongs to your endocrinologist, the doctor who specialises in glands and hormones, and nothing here changes that.

What does Graves' disease do to the eyes, and how common is it?

It can make the tissues around and behind the eyes swell, which causes bulging, puffy lids and dry, gritty eyes. The condition is called Graves' orbitopathy, Graves' eye disease or thyroid eye disease: three names for one problem. The National Eye Institute in the United States says about 1 in 3 people with Graves' disease develop some eye problems.

The immune system attacks the gland and, in some people, the muscles and fat inside the orbit, the bony socket the eyeball sits in. Other signs are lids that pull back, so a rim of white shows above the coloured part, lids that do not close fully, double vision and pain or pressure. It usually affects both eyes, but you may only notice one, which I explain in why one eye looks different in thyroid eye disease. Symptoms usually last 1 to 2 years and often settle on their own. Rarely, the swelling presses on the optic nerve, the cable from eye to brain, and sight is threatened.

In Malaysia, a 2008 study of 167 people with Graves' disease at two endocrine clinics found eye disease in 34.7 percent using American Academy of Ophthalmology criteria, and in 46.7 percent when lower lid retraction was counted too. The most common sign was a bulging eye, then lid retraction. More is in bulging eyes, gritty vision and puffy lids: could it be thyroid eye disease?

Can radioactive iodine cause thyroid eye disease?

It can trigger new eye disease or worsen existing eye disease in some people, and the risk is higher in some than in others. The Malaysian national guideline calls it a small but definite risk, especially in smokers, in severe hyperthyroidism (a badly overactive gland) and in recent-onset hyperthyroidism. Radioactive iodine is one of three treatments for an overactive thyroid; the others are antithyroid tablets and surgery.

The newest large figures come from Korea. A 2025 study used national health records for people with Graves' disease treated with radioactive iodine between 2008 and 2018. Of 12,819 treated, 453 (3.5 percent) were later recorded as having Graves' orbitopathy, compared with 4,007 (0.3 percent) of 1,529,386 people with Graves' disease who did not have radioactive iodine. The median time to onset was 18.7 months. Younger age, a shorter gap between diagnosis and radioactive iodine, and smoking raised the risk, while levothyroxine, the replacement thyroid hormone tablet, after treatment lowered it. Eye disease after radioactive iodine needed more intensive treatment, such as intravenous steroids and orbital radiotherapy.

Read this as an association in coded records, not proof of cause, because people offered radioactive iodine were not chosen at random. The 2018 European Thyroid Association guideline gives another figure, new or worsening eye disease in 15 to 33 percent of cases. Studies count different things, so neither is your personal chance.

That guideline says radioactive iodine is contraindicated, meaning not advised, in active or severe eye disease, and that low-dose steroid tablets around treatment (steroid prophylaxis) are warranted in mild active disease. The Malaysian guideline prefers antithyroid tablets or surgery when eye disease is active and moderate to severe, or sight-threatening. Whether steroid cover is right for you is for your endocrinologist and eye doctor to decide, so I give no doses. Thyroid eye disease and steroids explains what disease activity means.

Does smoking make thyroid eye disease worse, and what about vaping?

Yes. Smoking raises the chance of eye disease in Graves' disease, and the guidelines tell doctors to urge every person with Graves' disease to stop smoking, whether or not the eyes are involved. Nobody is being blamed. It is one of the few risk factors you can change.

The European guideline states that smokers have more severe disease, that eye disease after radioactive iodine is more frequent in smokers, and that smokers respond more slowly or less well to immune-suppressing treatment. In the Malaysian study, smokers with Graves' disease had 2.75 times the risk of eye disease of non-smokers, and 79 percent of the men in that group smoked. The Malaysian guideline asks for avoidance of cigarette smoke, active and passive, so smoke in the home matters too.

A 2026 study of 991 adults with newly diagnosed Graves' disease at one UK clinic found current smokers had 1.76 times the odds of orbitopathy. Each 10 cigarettes a day added 34 percent to the odds, and ex-smokers had risks comparable with non-smokers. It is one clinic and an association only.

Vaping is the obvious next question. No guideline reviewed recommends it as a substitute, and reliable evidence that it is safe for these eyes has not been shown, so I would not treat it as a safe swap. The aim is to stop with proper support, which your doctor can arrange.

Do my thyroid levels matter for my eyes?

Yes. The guidelines ask for thyroid hormone levels to be brought to normal quickly and kept there, because swings, particularly an underactive gland, are linked with worse eye disease. Normal levels are called euthyroidism. The European guideline asks that it be restored promptly and kept stable in everyone with eye disease.

The Malaysian guideline lists unstable thyroid tests, especially hypothyroidism, an underactive gland, as a risk factor. The European Thyroid Association names late correction of low thyroid levels after radioactive iodine as a risk for new eye disease, and the Korean study linked levothyroxine after treatment with lower risk.

The Malaysian guideline also says antithyroid tablets and thyroid surgery do not appear to change the natural course of the eye disease. The tablets do not cause the eye disease, and they do not clear it either. Please do not stop or change your thyroid medicine on your own; that decision belongs to your endocrinologist.

What should be checked in my eyes when Graves' disease is diagnosed?

At the least, someone should ask about eye symptoms, look at the eyes and lids, and refer you if anything is more than mild. The guidelines reviewed do not require a specialist visit for everyone on the day of diagnosis. I would want the eyes asked about, and looked at, at that first visit.

The Malaysian guideline lists early symptoms: redness of the eyes or lids, swelling or fullness of the upper lids, eyes that look too wide open, and pain in or behind the eyes. Pointers towards Graves' eye disease include thyroid disease of recent onset (within 18 months), symptoms that do not clear with antibiotic drops, new bags in the lids, and a change in how the eyes look. Morning puffiness alone has many causes, covered in puffy eyelids in the morning.

An eye assessment grades two things separately. Activity is whether inflammation is still switched on; the guideline uses a seven-point clinical activity score, and 3 or more means active. Severity covers lid position, swelling, how far the eye protrudes, eye movements and double vision, the cornea (the clear front window of the eye) and vision, including colour vision.

When should Graves' disease be referred to an eye doctor, and how urgently?

The Malaysian guideline says all cases except mild eye disease should be referred to specialised care, and urgently if sight is threatened. A doubtful diagnosis should be referred too. The European guideline adds that mild cases at risk should go to combined thyroid-eye clinics, where endocrine and eye expertise sit together. The usual route is your endocrinologist, or your family doctor with a referral letter.

The at-risk group is people with active disease, smokers, severe or unstable hyperthyroidism, and a high thyrotropin receptor antibody (TSHR-Ab) level, a blood test that is one of the listed risk factors. Urgent means same day, at an eye department or emergency department, for unexplained deterioration of vision, colours looking duller or different in one or both eyes, an eyeball slipped forward so the lids cannot cover it, a cloudy patch on the cornea, or eyes that clearly do not close. My article on the eyes that will not close properly explains why the cornea comes first.

Mild disease is watched, with preservative-free artificial tears for the dry surface. Operations to repair what remains are done after the disease has been inactive for at least 6 months, in the order decompression, squint, then lids. I describe the first step in orbital decompression. Newer infusion medicines are set out in what to ask before considering one, with no claim about availability here.

What can I ask my endocrinologist before choosing radioactive iodine, tablets or surgery?

Ask questions that put your eyes on the table. The choice is made with you and is theirs to make. I would want you to hold these as questions, not a script:

• Have my eyes been checked, and by whom, before this decision?
• Do I have any of the listed risk factors: smoking, severe or recent-onset hyperthyroidism, or a high TSHR-Ab?
• If radioactive iodine is planned, would steroid cover be considered for me, and who decides?
• After treatment, when will my thyroid level be checked, and when would replacement tablets start?
• If my eyes are already involved, would tablets or surgery suit me better than radioactive iodine?
• Who should I call if my eyes change, and how quickly?

You are the one who sees your eyes daily, so the last question is yours to ask first. The wider background is in the guide to what makes eyes look tired, and the other orbit conditions are under orbit and thyroid eye conditions.