Inside the eye are two fluid-filled cavities. The clear, watery eye fluid in the front chamber of the eye is called aqueous humor. This fluid is continually being formed in the ciliary processes near the lens. Drainage primarily occurs through a trabecular meshwork and into a tiny duct.
Glaucoma is a disease that affects drainage. The trabecular meshwork of the eye becomes damaged in people with glaucoma, preventing proper drainage of the clear fluid. This causes pressure to build within the eye. The result is that pressure begins to build in the back cavity. Increased pressure on the back of the eye can damage the optic nerve, resulting in loss of vision or even total blindness.
There are several eye drop medications commonly prescribed to treat people with glaucoma. One drug binds to receptors on the capillaries in the ciliary processes, causing them to constrict, thereby decreasing the amount of aqueous or clear fluid produced, thus reducing pressure.
Another drug acts on the uveoscleral pathway, which drains excess fluid into the part of the ciliary muscle beneath the trabecular meshwork. These drugs modify the cells that make up the ciliary muscle. This increases the size of the intercellular spaces through which the fluid can drain, therefore increasing outflow and decreasing pressure within the eye.