The direct cause of glaucoma is elevated intraocular pressure. Elevated intraocular pressure usually occurs due to developmental abnormalities, destruction of the eye structure due to external impact on the eye, or long-term use of hormone-containing medications. In patients with glaucoma, elevated intraocular pressure causes compression of the nerve fibers in the optic nerve area, resulting in disruption of axoplasmic transport of the nerve fibers and ultimately optic nerve atrophy. There are many causes of glaucoma. In addition to elevated intraocular pressure, the most common cause is a developmental abnormality called primary glaucoma. In addition, glaucoma can also be caused by a large external force to the eye that causes damage to structures such as the trabecular meshwork or the angle of the atrium, or by the long-term use of hormone-containing medications, which are known as secondary glaucoma. Patients with glaucoma should seek prompt medical attention to treat the cause of the disease.