Glaucoma.

Glaucoma is one of the major causes of blindness throughout the world. Rise in the intraocular pressure due to build up of the aqueous humor in the eye, causes Glaucoma. If left untreated, the rising fluid pressure damages the optic nerve, which is the main nerve of the eye linked to the brain, and results in loss of vision.
Aqueous humor is secreted constantly by the ciliary tissues. This fluid is responsible for the nourishment of your cornea, lens and the iris and for maintaining the shape of your eyes. It circulates in the space between the iris and the cornea. Since it is produced every hour, it also needs to be drained every hour. The ‘drainage angle’ is located at the point where the iris and the cornea meet. From here the fluid passes through the valve, dubbed the trabecular meshwork, which regulates the eye pressure, to the canal of Schlemm. From here, the fluid flows out of the eyes through a network of small veins, known as the drainage canals. If for some reason, there is some blockage in the normal drainage process the increased fluid build up in the eye increases the pressure on the optic nerve and if the condition remains for a long time, the optic nerve will suffer permanent damage.
Open Angle Glaucoma
Ninety percent of glaucoma cases are open angle glaucoma. It is also known as primary open angle glaucoma or chronic glaucoma. This occurs due to the blockage of the trabecular meshwork. In this type of glaucoma, the fluid build up occurs slowly. As a result, it takes considerable time for the sufferer to recognize the symptoms of the disease.