The Cornea and Thyroid Function

Thyroid disease can affect many organs throughout the body – and emerging research shows that the cornea may also be impacted, particularly in individuals with either hypothyroidism or hyperthyroidism. At the ELZA Institute, we assess the cornea holistically, including how systemic conditions like thyroid dysfunction may contribute to structural or functional changes.

How Thyroid Hormones Affect the Cornea

Thyroid hormones are involved in numerous metabolic and cellular regulatory processes, including those affecting the ocular surface, corneal metabolism, and collagen cross-linking. When hormone levels are abnormally high or low, these processes may be disrupted.

In hypothyroidism – whether congenital or acquired – changes in corneal parameters have been documented. Studies have shown that patients with congenital hypothyroidism may exhibit altered corneal curvature, increased central corneal thickness, and irregular topography. These alterations may remain subclinical but could contribute to symptoms such as blurred vision or contact lens intolerance.

Conversely, hyperthyroidism and its treatments, particularly radioactive iodine (RAI) therapy, have been associated with biomechanical corneal weakening. A Swiss case series reported the onset or progression of keratoconus shortly after RAI therapy, suggesting a potential link between oxidative stress, thyroid hormone fluctuation, and changes in corneal collagen stability.

The relationship

A connection between hypothyroidism and keratoconus has been suspected for decades:

In 1936, Appelbaum reported that patients with keratoconus have unusual signs of hypothyroidism.
In 1953, King showed that keratoconus is common after removal of the thyroid gland.
In 1999, Kocak described that autoimmune diseases of the thyroid lead to bilateral keratoconus.

Recognizing Subtle Corneal Changes

In some patients, corneal changes may remain asymptomatic and only be identified through corneal topography or tomography. These tools allow for detailed evaluation of curvature and structural regularity, which may be subtly affected in individuals with thyroid dysfunction.

In rare cases, thyroid-related corneal changes may contribute to or mimic conditions such as keratoconus, a progressive thinning disorder of the cornea. While not all patients with thyroid dysfunction develop corneal disease, those with risk factors – such as a family history of keratoconus or irregular astigmatism – may benefit from more detailed screening.

Hypothyroidism and corneal topography

A scientific article of Prof. Hafezi’s, published in 2014 in the Journal of Refractive Surgery clearly showed the association between hyperthyroidism and changes in corneal topography. Such changes are then accompanied by considerable fluctuations in vision.

Corneal Care in the Context of Thyroid Disease

At ELZA, we emphasize a comprehensive, multidisciplinary approach. For patients with thyroid dysfunction who present with unexplained visual changes or irregular corneal findings, we work collaboratively with endocrinologists and use advanced diagnostics to detect early biomechanical abnormalities.

If you have thyroid disease and are concerned about your vision or corneal health, a thorough examination – including high-resolution topography and biomechanical analysis – can help guide appropriate care.

Hypothyroidism and keratoconus

In this 53-year-old woman, keratoconus developed following a radioactive iodine therapy for Graves’ disease. No signs of keratoconus were present in the cornea prior to Graves’ disease.