Understanding the difference between thyroid disease and thyroid eye disease.
If you have dry eye and a thyroid condition, it is easy to make a direct connection:
“My thyroid must be causing my dry eyes.”
Sometimes thyroid-related disease really is relevant to the ocular surface. But there is an important distinction: having thyroid disease is not the same as having thyroid eye disease. And not every person with a thyroid disorder and dry eye has a thyroid-related eye problem. Understanding this difference can prevent a lot of confusion.
The thyroid is a gland in the neck that produces hormones involved in regulating metabolism and many other functions throughout the body. Several different disorders can affect it. Two broad possibilities are:
These are descriptions of thyroid function. They do not tell us whether someone has thyroid eye disease.
Thyroid eye disease (TED) is an autoimmune inflammatory disease affecting tissues around the eyes. You may also see it called:
It is most commonly associated with Graves’ disease, but the relationship is not absolute. TED can occur in people who are hyperthyroid, hypothyroid or even euthyroid, meaning that their thyroid hormone levels are within the normal range. So:
abnormal thyroid hormonesdoes not equalthyroid eye disease
And normal thyroid hormones do not completely exclude thyroid eye disease. These are related but different parts of the thyroid-autoimmune picture.
TED affects tissues within and around the orbit. Depending on the person and severity, it can cause changes such as:
In more severe disease, vision-threatening complications can occur. But for our dry-eye guide, the particularly important question is what happens to the ocular surface.
For a long time, the most intuitive explanation was mainly mechanical. If the eye projects farther forward and the eyelids retract, more ocular surface is exposed to air. The eyelids may also have difficulty closing completely. More exposure can mean:
That mechanism is real. But it is not the whole story. Modern research suggests that ocular-surface disease in TED involves several interacting mechanisms, including exposure, inflammation, lacrimal-gland dysfunction, altered blinking and meibomian-gland abnormalities.
Yes. The lacrimal glands themselves can be involved in TED. Research describes inflammatory changes and dysfunction of the lacrimal glands as one potential contributor to abnormal tear secretion and ocular-surface disease. This is important because it means TED-related dry eye is not necessarily purely evaporative. Someone may have both:
Again, the actual ocular findings matter more than simply assigning a dry-eye subtype based on the systemic diagnosis.
TED can alter normal eyelid mechanics. Eyelid retraction, proptosis and other orbital changes may make blinking less effective or contribute to incomplete eyelid closure. If a blink does not adequately cover the ocular surface, the tear film may not be redistributed normally. And if the eyelids do not close completely during sleep, additional exposure can occur. We already discussed this mechanism in our article on Eyelid & Exposure Conditions. TED is one example of a disease that can create that exposure.
Evidence suggests that meibomian-gland dysfunction can also be part of the ocular-surface picture in TED. Recent reviews describe meibomian-gland abnormalities alongside altered blinking, lacrimal-gland dysfunction and ocular-surface inflammation. But, as always, we need to be careful with causality. MGD is extremely common. So TED plus MGD does not automatically prove that TED caused all of the gland dysfunction.
It tells us that both may need to be considered when evaluating the ocular surface.
Meibomian Gland Dysfunction (MGD) — coming soon
No. Graves’ disease is an autoimmune disorder involving the thyroid. Thyroid eye disease is an autoimmune disease affecting tissues around the eyes. They are strongly associated, but they are not identical.
Someone can have Graves’ disease without developing TED. And TED can occasionally occur without current hyperthyroidism. This is why the phrases “Graves’ disease” and “thyroid eye disease” should not simply be used interchangeably.
TED is much more strongly associated with Graves’ disease. However, thyroid-associated orbitopathy can occur in people with other autoimmune thyroid states, including hypothyroid or euthyroid patients. That does not mean that a person with Hashimoto’s disease and dry eyes should assume they have TED. Those are two separate findings until there is clinical evidence connecting them.
Not necessarily. This is particularly important because both thyroid disorders and dry eye are common. Two common conditions can occur in the same person without one being the sole cause of the other. Population studies have reported associations between systemic thyroid disease and dry eye, but an association cannot establish the cause of dry eye in an individual patient.
A person with hypothyroidism can also have:
So the thyroid diagnosis is relevant medical history. It is not automatically the explanation.
Possible symptoms include:
But these symptoms are not specific. Dryness, burning and redness can occur in many forms of ocular-surface disease. That means dry-eye symptoms cannot diagnose thyroid eye disease. The diagnosis depends on the broader clinical picture.
Depending on the presentation, clinicians may look for features such as:
The patient’s thyroid and autoimmune history also matters. If TED is suspected, evaluation may involve ophthalmic examination, thyroid-related laboratory testing and, when appropriate, orbital imaging.
Yes. This often surprises patients. Because TED and thyroid dysfunction are related, it seems logical that normal thyroid hormone levels should exclude the eye disease. But they do not.
TED can occur in euthyroid patients. This does not mean that unexplained dry eye plus normal thyroid tests should lead someone to suspect TED. There still need to be clinical reasons to consider the diagnosis. It simply means that normal thyroid function tests alone are not a universal rule-out test for TED.
Not necessarily. Managing thyroid dysfunction is important, but TED is an autoimmune orbital disease rather than simply a direct consequence of having too much or too little thyroid hormone. The orbital disease can therefore follow its own course. Likewise, ocular-surface problems may persist even when systemic thyroid levels are well controlled.
This is another reason to separate thyroid function from thyroid eye disease, and both from dry eye disease. They interact, but they are not the same condition.
It can, particularly when the treatment improves mechanisms contributing to exposure or orbital inflammation. But dry-eye management may still be necessary. A 2024 systematic review found evidence that several topical and non-topical treatments can improve ocular-surface symptoms or signs in TED, but the available studies were limited and heterogeneous, so the authors could not identify one clearly superior management approach. This fits the broader TFOS DEWS III principle: dry-eye treatment should be directed toward the actual etiological drivers identified in the individual patient.
Rather than simply saying “Your thyroid is causing your dry eye,” it is more useful to ask what is actually happening. For example:
This is much closer to the etiological approach recommended by TFOS DEWS III, where dry eye is understood as a multifactorial disease and individual drivers are identified rather than inferred from one diagnosis in the medical history.
Wolffsohn JS, et al. TFOS DEWS III: Diagnostic Methodology.
Current framework for identifying individual etiological drivers of dry-eye disease.
Jones L, et al. TFOS DEWS III: Management and Therapy.
Evidence-based framework emphasizing management directed toward the relevant dry-eye etiological drivers.
Wong AS, Chelnis JG. Systematic Review of Ocular Surface Treatments in the Setting of Thyroid Eye Disease.
Review showing that TED-related ocular-surface disease involves mechanisms beyond simple corneal exposure.
Wang Y, et al. Research Progress on the Immune Mechanism of Thyroid-Related Eye Disease Combined With Dry Eye.
Review of immune inflammation and abnormalities involving tear secretion, tear quality and eyelid dynamics in TED-associated dry eye.