What is Glaucoma?
Glaucoma is the term that refers to a group of eye diseases that cause damage of the optic nerve. The symptoms of glaucoma may not be present until the disease is at advanced stage when loss of central vision occurs. Thus, glaucoma is called “silent thief of sight”. High intraocular pressure is not always the cause of glaucoma although it increases the risk for the disease. Actually, glaucoma may develop even if the eye pressure is normal or below normal. Glaucoma is the leading cause of blindness worldwide. Glaucoma affects around 3 million people in the United States and in 120,000 of affected glaucoma has caused blindness.
High Intraocular Pressure and Glaucoma
Elevated ocular pressure is the major cause of damage of the optic nerve. This pressure is the result of accumulation of aqueous humor, a clear fluid present in the front of the eye. Aqueous humor is constantly produced by the ciliary body, positioned directly behind the iris. This fluid then flows between the iris and the crystalline lens into the anterior chamber. Aqueous humor leaves the eye through drainage angle of the eye that consists of tiny channels known as trabecular meshwork. Usually, intraocular pressure becomes elevated due to either excess production of aqueous humor within the eye or blocked trabecular meshwork. In both cases, the eye cannot remove increased fluid which results in elevated pressure and damage to the optic nerve. The optic nerve normally transmits signals to the brain, but as optic nerve fibers die off the signals cannot be passed to the brain, thus cannot be seen. Commonly, people with glaucoma first lose peripheral vision because optic nerve fibers within peripheral retinal cells are initially affected.
Symptoms and Types of Glaucoma
Symptoms of glaucoma mainly depend on the type of glaucoma, but they also differ from patient to patient.
Primary Open Angle Glaucoma
This type of glaucoma generally does not produce symptoms early in the course of the disease. The first symptom patients typically experience is progressive peripheral vision loss.
Acute Angle Closure Glaucoma
This type of glaucoma is followed by severe eye pain, headache, nausea, vomiting, blurred vision and haloes around lights. This disease requires immediate medical treatment or otherwise irreversible blindness occurs within days.
Normal Tension Glaucoma
There are no early symptoms associated with this type of glaucoma. Permanent vision loss is the first indicator of normal tension glaucoma.
Symptoms of congenital glaucoma are enlarged eyes and cloudy corneas.
Early symptoms of pigmentary glaucoma may not be present. Haloes, blurred vision and eye pain are possible symptoms.
Treatment for Glaucoma
Glaucoma cannot be cured and damage it causes is irreversible. However, treatment can prevent or slow vision loss if glaucoma is diagnosed early. Treatment for glaucoma aims to lower eye pressure with eye drops and medications. Eye drops are used to reduce production of eye fluid or to improve its drainage. Most commonly used glaucoma medications include beta blockers, alpha-2 agonists and prostaglandin analogs.