Association of Hypothyroidism with Glaucoma: A Recent Update

The association of hypothyroidism with glaucoma is conflicting. Many population-based surveys showed an association of hypothyroidism including sub clinical hypothyroidism (SCH) with primary open angle glaucoma, while studies in some other population could not support such association. Though the conclusion about the role of thyroid hormone on ocular parameters is debatable, many studies reported that hypothyroidism could make changes in the interstitial connective tissue matrix, increased capillary density and increased serum lipid levels that may result in choroidal thickening. Hypothyroidism can increase the synthesis of glycosaminoglycans in the trabecular meshwork, result in a reduced aqueous outflow and, thereby, increased the intraocular pressure (IOP). An elevated IOP even in patients with SCH can lead to glaucoma. Furthermore, hypothyroidism increases the homocysteine level which will induce the death of retinal ganglion cells either by direct cytotoxic effect or mediated through oxidative stress. This review article discusses the possible association of hypothyroidism and glaucoma.