Knowing the Types of Glaucoma
What is Glaucoma?
When the eye’s optic nerve is damaged to permanently impair vision, progressing to complete blindness if untreated, you have an eye disorder called Glaucoma. Considered a leading cause of irreversible blindness among more than 3 million blind Americans, the condition is progressive, starting with a subtle loss of side or peripheral vision. If left on its own, glaucoma progresses to a loss of central vision and sufferers go blind. Glaucoma is sinister. If the symptom of reduced visual acuity is experienced, it means Glaucoma is already in its later stages.
Understanding the Symptoms
The onset of glaucoma has no early symptoms and the symptoms associated with it only appear when it’s too late and vision starts to diminish. There are generally two primary glaucoma types with different symptoms. Open-angle glaucoma is the most common accounting for 90% of all cases in the US. The eyes' drainage system gets progressively blocked over time so that intraocular pressure builds up slowly. This could be taking place for years without symptoms until the optic nerve gets affected so that a gradual loss of peripheral vision is felt - the primary symptom.
Closed-angle or angle closure glaucoma is the other type accounting for 10% of cases in the US, but can occur in half of the cases in Asian nations. Here, the eye's drainage system gets suddenly blocked, swelling and reddening the affected eye and causing acute severe pain that often comes with nausea, diminished vision (central and side), and perceived halos around lights. The condition is a medical emergency. Left untreated, it can result in complete loss of vision within 24 to 48 hours.
Normal Pressure Glaucoma is an open-angle variant that occurs when there’s no intraocular pressure build-up and the pressure is normal. What causes progressive nerve damage, this time, is decreased blood supply to the nerve. This is a recent discovery that debunks the earlier held generalization that high intraocular pressure exclusively causes glaucoma. You get the same symptoms as any open-angle glaucoma.
Complete blindness from either of the primary open and closed angel glaucoma is called Absolute Glaucoma, the final stage of the disorder. Apart from total blindness, the condition is often accompanied with intermittent pain in the affected eye.
Causative and Risk Factors
Glaucoma is often associated with ocular hypertension or intraocular pressure (OP) a condition of increased fluid (aqueous humour) pressure in the eye which causes a progressive deterioration of the optic nerve. The exception comes with normal tension glaucoma. This causative factor accounts for 50% of those suffering from open angle glaucoma.
Anyone can suffer glaucoma but some are at a higher risk than others. Advancing years increase the risk starting at age 45 and people in their 60s and older have more chances of developing one. The condition is suspected as hereditary, so that if your family has a history of glaucoma in previous generations, you have a higher risk to it. While the predisposition is inherited and develops in adults, a relatively rare case is congenital glaucoma when an infant is born with a dysfunctional eye drainage that results in increased intraocular pressure and eventual loss of vision. Infants and toddlers with the condition suffer from an enlargement of the eyeball since it is more pliant at this age.
Race is another. Latinos and African Americans have been documented to have five times more susceptibility to Glaucoma and four times more chances of going blind from it than Caucasians. East Asians are also more susceptible to developing closed angle glaucoma due to a shallower anterior chamber distance
A relatively uncommon type is neovascular glaucoma caused by central retinal vein occlusion (CRVO) or proliferative diabetic retinopathy (PDR). This is nearly impossible to cure and can be triggered by an ischemia or thinning of the retinal nerves that restrict blood supply to the retina.
Glaucoma caused by existing ailments and medical conditions or prolonged medication are called secondary glaucomas. People with severe myopia or nearsightedness as well as farsightedness, diabetes and hypertension are at a higher risk since these conditions increase eye pressure that can damage optic nerves.
Secondary glaucomas also arise in patients with prolonged use of steroids when medicating certain ailments that require steroids (steroid or corticosteroid-induced glaucoma). These are commonly known as drug-induced glaucoma which also includes alpha-chymotrypsin glaucoma caused by the use of the drug to control postoperative ocular hypertension.
Injury to the eye that happened years ago can also cause progressive glaucoma. Moreover, inflammation of the iris, retinal detachment or retinal vein occlusion or blockage can starve the optic never cells to death and cause secondary glaucoma.