Hypothyroidism is the most common thyroid disorder where the thyroid gland does not produce enough thyroid hormones and slow down metabolism. Although thyroid hormones affect nearly every organ in the body, the majority of previous studies focus on organs such as heart, brain, muscles, skin, gastrointestinal and reproductive systems, while less information is known regarding the effects of hypothyroidism on the eye. Recent studies have suggested association of hypothyroidism with the two leading causes of irreversible visual impairment by age-related macular degeneration and glaucoma in the eye. Furthermore, recently it has also been found that thyroid hormone receptors exist in the cornea and the retina of the eye and thyroid hormones regulate the retinal cone photoreceptor expression. Therefore, it is critical to investigate the effects of hypothyroidism on the eye.
In this proposed study, ocular structure and function parameters including central and peripheral corneal thickness, corneal volume, corneal hysteresis and resistance, topographic mapping of macular structure, macular neuronal response function, and perceptual color contrast sensitivity of the macula will be measured and compared in 30 subjects with newly diagnosed hypothyroidism before and after treatment as well as age-matched controls. Correlation of the systemic thyroid hormone changes with changes of the ocular parameters will be analyzed. The results of this study will not only provide valuable information on structure and function of the eye in hypothyroidism, the therapeutic effect of systemic treatment on the ocular structure and function, but also has significant potential in early diagnosis and treatment of hypothyroidism in patients with subtle ocular signs.