Doctor's Notes on Primary Open-Angle Glaucoma (POAG)
Primary open-angle glaucoma (POAG) is the most common type of glaucoma. It is one of the leading preventable causes of blindness in the world, and it is the most common cause of blindness in African-Americans. In POAG, there is the characteristic optic nerve damage associated with open angles (the area between the iris and cornea) and elevated eye pressure. This is different from other types of glaucoma, which are associated with abnormal angles (for example, narrow-angle glaucoma, closed-angle glaucoma, primary congenital glaucoma, and other secondary glaucomas) or low eye pressures (normal tension glaucoma).
In the early stages, primary open-angle glaucoma may cause no symptoms. The main signs of primary open-angle glaucoma are
- the presence of a thinned (atrophied) optic nerve and the presence of an open angle,
- both of which can be seen using specialized instruments during an eye examination.
By the time symptoms of vision loss or blind spots in primary open-angle glaucoma occur the disease is usually in the later stages and irreversible optic nerve damage may have already occurred.
What Is the Treatment for Primary Open-Angle Glaucoma?
Primary open-angle glaucoma is treated with medications or surgery. Medications prescribed for open-angle glaucoma are designed to either increase the outflow of fluids in the eye or decrease the overall production of fluids in the eye in order to keep intraocular pressure under control. Drug combinations are often used to control intraocular pressure because they have a greater benefit than any single drug used by itself. Common drug classes used to treat open-angle glaucoma include:
- Alpha adrenergic agonists
- Cholinergic agonists
- Rho kinase inhibitors
- Beta blockers
- Carbonic anhydrase inhibitors
- Combination products are available for several classes of drugs including most commonly:
Some cases require a surgical procedure to keep intraocular pressure under control. Common glaucoma treatment procedures include
- Laser therapy (trabeculoplasty)
- Argon laser trabeculoplasty
- Surgical therapy (trabeculectomy) with creation of a filtration bleb
- Placement of mechanical shunts
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Adult Glaucoma SuspectGlaucoma is usually high pressure inside the eye that damages the optic nerve and can result in permanent vision loss. Various exams and tests are used to diagnose the disease.
Angle Recession GlaucomaAngle recession glaucoma refers to a group of ocular disorders that occur after the eye undergoes trauma. Following this trauma, different mechanisms can cause an abnormal elevation of pressure inside the eye. An ophthalmologist diagnoses angle recession glaucoma using special instruments. Treatment may include eye drops, medication, laser surgery, or conventional incisional surgery. Taking steps to prevent traumatic eye injury is the best way to prevent angle recession glaucoma.
GlaucomaGlaucoma can be caused by a number of eye diseases that can damage the optic nerve, typically by elevating pressure inside the eye, which is called intraocular pressure (IOP) or ocular hypertension. Symptoms begin slowly and include vision loss and irregularities, eye pain, headache, nausea, and vomiting. Beta-blockers, Alpha-adrenergic agonists, and prostaglandin analogs are drugs used to treat glaucoma. Sometimes surgery is necessary, especially with congenital glaucoma. The disease is not curable but can be managed.
Glaucoma FAQsGlaucoma is usually high pressure inside the eye that damages the optic nerve and can result in permanent vision loss. While high pressure inside the eye, damage to the optic nerve and vision loss are common criteria for diagnosing glaucoma, glaucoma can be present without all three of these criteria. The two main types of glaucoma are open-angle and angle-closure glaucoma. Glaucoma may be symptomless until significant permanent vision damage has occured, but may show symptoms as well, including pain, redness, haloes, and blurred vision.
Glaucoma MedicationsGlaucoma is a disease characterized by increased intraocular pressure (IOP). (Intraocular means within the eye.) Increased intraocular pressure results from either increased production or decreased drainage of aqueous humor. Treatment for glaucoma can include medication and/or surgery to lower the intraocular pressure.
Lens-Particle GlaucomaLens-particle glaucoma is a form of glaucoma that occurs due to leakage of material from the inside of the lens of the eye. It may be caused be trauma, surgery, or inflammation. Signs and symptoms of lens-particle glaucoma may include blurred vision, sensitivity to light, eye pain, headache, redness, and tearing. The condition is diagnosed by ophthalmologic evaluation. Treatment may include eyedrops to control eye pressure and inflammation.
Normal-Tension GlaucomaNormal-tension glaucoma or low-tension glaucoma is a condition in which the optic nerve is damaged despite normal fluid pressure inside the eye (other types of glaucoma result vision loss because of abnormally high pressure inside the eye. Normal-tension glaucoma typically occurs in older adults and can be caused by congenital nerve defects and irregularities in blood flow to the eye. Eyedrops and surgery are treatments for this disorder.
Ocular HypertensionThe term ocular hypertension usually refers to any situation in which the pressure inside the eye, called intraocular pressure, is higher than normal. Typically, those with ocular hypertension have any symptoms or signs. Treatment typically involves medicated eyedrops to help lower intraocular pressure.
Primary Congenital GlaucomaPrimary congenital glaucoma is present at birth and may be inherited. Blepharospasm, photophobia, and epiphora are symptoms. A cloudy whitish-gray cornea is a common sign. Treatment of primary congenital glaucoma typically involves surgery.
What Is Usually the First Sign of Glaucoma?Early glaucoma usually has few symptoms, but the buildup of pressure in the eye over time leads to slow vision loss starting with peripheral vision.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.