Diagnosis and Testing for Thyroid Eye Disease
Reviewed by: HU Medical Review Board | Last reviewed: October 2021 | Last updated: September 2023
Incorrect or delayed diagnosis of thyroid eye disease (TED) is not uncommon. Because TED is rare, seeing a specialist early and getting the right diagnosis is important to help prevent complications. These specialists are ophthalmologists who are eye doctors with special training and experience treating and diagnosing TED.1,2
The first step in diagnosing TED is having a full physical examination from a TED specialist.2
A detailed, accurate medical history and physical exam are needed to get the right diagnosis of TED. You play an important and active role in the process.3
Describing your medical history as detailed as possible ensures your doctor gets all the information needed to treat your symptoms. This may not be easy. Do your best to remember when your symptoms or discomfort started. What made you come in to see the doctor? How would you describe your symptoms? Is there anything that makes your symptoms better or worse?
Describe and list any diseases or illnesses you have had, even if they happened in childhood.
Health and lifestyle habits
The health of your immediate family members may offer important clues about your current health. Your doctor may ask questions about family medical history for this reason.
When asked about your lifestyle habits, be open and honest with your doctor. Habits like smoking significantly increase the risk of developing TED.3,4
During the eye exam, your doctor can perform a number of different tests and determine if you need any follow-up tests. These tests help evaluate your overall eye health.1
Swelling of the eyelids, increased eye pressure, and eye protrusion are symptoms of TED. Your TED specialist will assess these as part of your detailed eye exam.5
An exophthalmometer (ek-sof-thul-mom-i-ter) is a special ruler your TED specialist will use to measure the amount of forward bulge in your eyes. This forward bulging is called proptosis (prop-toe-sis) or exophthalmos (ek-sof-thal-mis).5
This measurement will be taken at all your visits to the TED specialist. While many people with TED have proptosis, some do not.5,6
As part of your eye exam, your TED specialist will use an ophthalmoscope (off-thal-muh-skohp) to look for signs of damage to the optic nerve. An ophthalmoscope is a tool that helps visualize the back of the eye and optic nerve.7,8
The eye doctor may give you eye drops to enlarge (dilate) your pupils to get a better look at the nerve at the back of your eye.7,8
Clinical activity score
The clinical activity score (CAS) is a 7-point scale used by your TED specialist to help aid a TED diagnosis. The scale uses classic signs and symptoms of active TED. Each sign or symptom that is present is given a point. A score of 3 or more indicates active disease:6,9
- Eye pain at rest
- Eye pain when eyes are moving
- Eyelid swelling
- Red eyelid
- Redness of the tissue that lines the eyelid and outside of the eyeball (conjunctiva)
- Swelling of the conjunctiva that can look like fluid or a blister (chemosis)
- Inflammation of the inner corner of the eye (caruncle or plica)
Blood tests will be ordered to check your thyroid hormone levels and help with diagnosing TED. These include:10,11
- Thyroid-stimulating hormone (TSH), which is a hormone produced in the pituitary gland of the brain. TSH tells the thyroid gland to make thyroid hormones.
- Triiodothyronine (T3) and thyroxine (T4), which are hormones made in the thyroid but controlled by the pituitary gland in the brain. These are both typically high in those with Graves’ disease, an autoimmune disease that causes an overactive thyroid (hyperthyroidism). Graves’ disease may occur with TED, but neither disease causes the other.
- Thyroid-stimulating immunoglobulin (TSI), the antibody present in those with Graves’ disease. A positive result proves Graves’ disease.
- Thyroid stimulating hormone receptor antibody (TRAb), which is another harmful antibody that may or may not be present in those with Graves’ disease.
- Anti-thyroid peroxidase antibody (anti-TPO), which is a harmful antibody that is usually found in those with Graves’ disease. This antibody is also found in those with Hashimoto’s disease, an autoimmune thyroid disease that leads to low thyroid function (hypothyroidism).
Your doctor may order imaging tests if other tests do not provide a diagnosis. These may include CT scans or MRI imaging of your thyroid or eye sockets (orbits).6,12
Because TED is rare, diagnosis may be delayed. Understanding more about TED as well as finding a TED specialist will help prevent these delays.