Hashimoto’s thyroiditis is the most common cause of hypothyroidism, a condition where the thyroid gland does not produce enough hormones. This autoimmune disorder causes the body’s immune system to mistakenly attack the thyroid tissue. While its primary effects involve the thyroid and metabolism, Hashimoto’s is a systemic disease that can impact other organs. The eyes are one area that can be affected by the underlying autoimmune and inflammatory processes.
Understanding the Autoimmune Connection
Hashimoto’s thyroiditis and Graves’ disease are both autoimmune disorders that target the thyroid, leading to hypothyroidism and hyperthyroidism, respectively. In Graves’ disease, the immune system often produces thyroid-stimulating antibodies (TSAb) that cause significant inflammation and severe symptoms known as Thyroid Eye Disease (TED). Eye involvement is seen in approximately 25% of Graves’ patients.
Eye issues in Hashimoto’s are less common, affecting about 6% of patients. The eye disease is usually milder and less likely to involve the severe proptosis (bulging) or double vision characteristic of Graves’ TED. While Hashimoto’s is characterized by antibodies like TPOAb and TgAb, severe orbital changes are thought to occur when patients also have detectable levels of TSAb, similar to Graves’ disease.
The autoimmune process, even without severe orbitopathy, can trigger chronic, low-grade inflammation affecting the structures surrounding the eyes. This systemic inflammation leads to specific ocular issues that fluctuate with the autoimmune disorder’s activity and the patient’s thyroid hormone levels.
Specific Ocular Manifestations and Causes
Dry Eye Syndrome (DES) is one of the most common ocular complaints among individuals with Hashimoto’s, often causing a gritty sensation, burning, or blurred vision. Autoimmune inflammation can directly affect the lacrimal glands, leading to decreased tear quantity. Furthermore, inflammation can alter the tear film composition, causing increased tear evaporation and an unstable ocular surface.
Patients may also experience mild upper eyelid retraction (UER), which gives the appearance of a wide-eyed stare. UER occurs when inflammatory changes or altered muscle tone affect the levator palpebrae superioris muscle controlling the upper eyelid. This subtle retraction contributes to dry eye symptoms by exposing more of the ocular surface and accelerating tear evaporation.
Another frequently reported manifestation is periorbital edema, or swelling around the eyes. This is linked to the generalized fluid retention and systemic inflammation associated with hypothyroidism, causing tissues around the eyes to become boggy. The swelling may be accompanied by a feeling of pressure or discomfort behind the eyes.
Blurred vision and increased light sensitivity (photophobia) are secondary symptoms stemming from underlying dryness and surface irritation. When the cornea is not properly lubricated due to DES, its surface integrity is compromised, leading to scattering of light and visual disturbances. In rare instances, Hashimoto’s can lead to significant orbitopathy involving the enlargement of extraocular muscles, potentially causing double vision or pressure on the optic nerve.
Diagnosis and Management Strategies
The initial step in addressing eye symptoms requires a collaborative approach involving an endocrinologist and an ophthalmologist. The endocrinologist focuses on optimizing thyroid hormone levels, as maintaining a stable euthyroid state minimizes systemic inflammation and disease activity. The ophthalmologist uses diagnostic tools like the Schirmer test to quantify tear production, and orbital imaging, such as MRI, if muscle swelling or proptosis is suspected.
The primary management strategy for common dry eye symptoms involves symptomatic relief through local treatments. Over-the-counter artificial tears are the first line of defense to lubricate the eye and stabilize the tear film; preservative-free options are recommended for frequent use. Thicker lubricating gels or ointments can be applied before sleep for prolonged moisture overnight.
For more persistent or inflammatory dry eye, prescription eye drops, such as those containing cyclosporine or lifitegrast, can reduce inflammation and promote natural tear production. In cases of severe dryness, a minor procedure called punctal occlusion inserts small plugs into the tear ducts, preventing tears from draining too quickly and keeping the eye surface moist.
Systemic management may involve anti-inflammatory medications if significant orbital inflammation is present, though this is rare in Hashimoto’s. For mild to moderate orbitopathy, selenium supplementation, under a doctor’s guidance, may help reduce local inflammation. Lifestyle adjustments are also beneficial, including wearing wraparound sunglasses outdoors and using humidifiers indoors to maintain air moisture.