While proptosis may be one of the hallmark symptoms of thyroid eye disease, in reality, the condition is far more complex and challenging than meets the (bulging) eye.
Other symptoms include double vision, dryness, pain, grittiness, and excessive tearing, along with bloodshot eyes, swelling, and puffiness. Left unchecked, more severe and rarer presentations of thyroid eye disease can lead to decreased, blurry, or loss of vision.
"Severe disease can be sight threatening due to injury to the optic nerve or the surface of the eye," Rachel Arakawa, MD, an endocrinologist at Mount Sinai Health System in New York City, told 鶹ý.
In addition to these symptoms, eyelid retraction is also possible in more serious cases, leading some patients to be unable to fully close their eyes.
"Patients with thyroid eye disease may have eyes that point in different directions because of poor alignment," added Terry J. Smith, MD, of Kellogg Eye Center at the University of Michigan in Ann Arbor.
Around half of people with Graves' disease develop thyroid eye disease, an autoimmune disease driven by , he told 鶹ý. Roughly 6% of these patients will go on to experience some level of color vision loss as well, "most frequently the consequence of optic nerve damage, which can lead to blindness."
Smith noted that total loss of vision with this condition is "very rare."
However, presentation of any of these more serious symptoms "should trigger an urgent evaluation by an ophthalmologist," warned Arakawa.
Pitfalls of Misdiagnosis
Despite the myriad specific symptoms related to thyroid eye disease, actually getting a formal diagnosis can sometimes prove to be a challenge.
"There are no blood tests or imaging studies that can prove a patient has thyroid eye disease," Robert A. Goldberg, MD, an ophthalmologist at the Stein Eye Institute at UCLA Health in Los Angeles, told 鶹ý.
"The testing can support the diagnosis -- if the blood tests are positive or if the scan shows typical features of eye muscle enlargement," he added, "but patients can still have thyroid eye disease with negative testing."
Goldberg pointed out that the common clinical features of the disease, like eye bulging, orbital swelling, eyelid retraction, and restriction of eye movement, can often be recognized by experienced physicians, prompting diagnosis even in the absence of positive tests.
"This can all be a bit complicated so that doctors unfamiliar with thyroid eye disease sometimes have difficulty making the diagnosis," he explained.
On top of testing issues, sometimes patients don't even recognize that their eye symptoms are related to their underlying thyroid disease, Arakawa said.
"Most patients don't recognize an immediate link between their thyroid gland and their eyes, but autoimmune thyroid disease has systemic effects that affect many body parts," she noted, adding that this condition can often follow an "unpredictable course."
For example, thyroid eye disease can manifest at any point in a patient with Graves' disease, sometimes even preceding the onset of hyperthyroidism. On top of that, it can also impact patients with Hashimoto's thyroiditis.
Triggers of Disease
Uncontrolled forms of either of these conditions can be a trigger of thyroid eye disease, Arakawa pointed out, as well as cigarette smoking, radioactive iodine therapy, female sex, and increasing age.
"Rarely, it can also occur during normal thyroid function and during hypothyroidism," she said.
Smith added that because the typical symptoms of thyroid eye disease mirror so many other eye conditions, it can often be mistaken as allergies or conjunctivitis. These misdiagnoses only lead to a further delay in appropriate treatment.
"Some may mistakenly assume their eye symptoms are simply another feature of Graves' disease and that it should be treated with the same medications prescribed by their endocrinologist," he said. "But [this] is a different disease, requiring different management provided by a thyroid eye disease specialist, such as a neuro-ophthalmologist, pediatric ophthalmologist, oculoplastic surgeon, or optometrist with special training in diagnosing and treating thyroid eye disease."
Goldberg recommended these patients see an expert ophthalmologist with oculofacial training in order to properly determine if thyroid eye disease is present.
According to the clinical practice guidelines for the medical management of Graves' orbitopathy, "early referral to specialized centers is fundamental for most patients with [thyroid eye disease]."
Barriers to Specialty Care
Although this type of subspecialty care is pivotal to proper diagnosis, access can pose a whole new slew of challenges to the patient.
"Wait times for subspecialty care are often prolonged and up to months long, which can delay the time it takes to make an accurate diagnosis," said Arakawa.
"If a patient is able to have an ophthalmology evaluation first, they will likely be referred to an endocrinologist to obtain a formal diagnosis of thyroid disease and begin treatment with antithyroid drugs," she said. "Conversely, if they initially present to an endocrinologist with complaints of hyperthyroidism and are found to have eye disease, they will be referred to an ophthalmologist who specializes in thyroid eye disease for evaluation."
"Either way their care will need to be a team effort with joint input from their endocrine and ophthalmology physicians to craft their treatment plan," she added.
Disclosures
Arakawa and Goldberg reported no disclosures. Smith reported a relationship with Horizon Therapeutics.