The Different Kinds of Glaucoma You Need to Know About

Glaucoma is often thought to be a particular eye disease. However, when most people talk about glaucoma, they usually refer to open-angle glaucoma which is the most common type, affecting about 80-90% of individuals. This is one of two main forms of the disease the other being angle-closure glaucoma. Additionally, there are other lesser known forms of the condition.

Knowing all these other types of glaucoma is vital because they have different causes and different people are susceptible to these various forms. Thus, understanding what causes these glaucomas will help you know whether you are vulnerable to a particular type.

This article aims to help you know and understand the different forms of glaucoma, what causes them, and whether you are at risk of getting a particular kind(s).

Glaucoma is a term used to define the group of eye diseases which cause the gradual loss of vision by damaging the optic nerve permanently. The optic nerve is that nerve which transmits images to the brain.  Currently, glaucoma is the 2nd leading cause of irreversible blindness in the world.

Types of Glaucoma

• Primary Open-Angle Glaucoma (POAG)

It is the most prevalent form of glaucoma in the U.S with at least one percent of all Americans having this kind of glaucoma.   It is common for people over 50 years of age.

POAG often has no symptoms. Pressure inside the eye builds up gradually thus causing the cornea to adapt hence resulting in no swelling. The significance of a swollen cornea is that it indicates something is not right plus the following symptoms. However, as this is not the case with POAG, the disease often goes unnoticed. This makes the condition painless, and the victim rarely realizes that they are slowly vision until the final stages of the disease. By this time, however, the damage is usually irreversible. 

Because POAG does not show abnormalities in the trabecular meshwork, it is believed that the root of the condition lies in the inability of cells in the trabecular meshwork to perform their normal functions. Additionally, it could be as a result of the presence of fewer cells due to the natural process of aging. Another theory postulates that the problem is caused by structural defects in the eye’s drainage system. Another suggests that enzymatic issues are the cause. All of these arguments are currently under study.

In glaucoma, the problem is usually directly related to the increase in intraocular pressure (IOP). 16mmHg (millimeters of mercury) is considered to be the average IOP in a normal population. An IOP of 20mmHg is still considered to be within the normal range. However, an IOP of 22mmHg is deemed to be abnormal and therefore suspicious. It is vital to note that not all elevated IOPs result in glaucoma.

As earlier mentioned, a pressure increase in the eye can destroy optic nerve cells. Once a substantial number of these cells are damaged, blind spots will begin appearing in your field of vision. Typically, these blind spots will first start forming in the outer sides of the field of vision. The central view is affected during the later stages of glaucoma. Once vision loss occurs, the damage is irreversible because the nerve cells are dead.

POAG is classified as a chronic disease and is considered to be hereditary. At the moment, there is isn’t a cure yet but the condition can be slowed down by treatment.

• Normal Tension Glaucoma
low-tension glaucoma, this glaucoma type is characterized by the progressive damage to the optic nerve at a statistically normal IOP. Normal tension glaucoma accounts for 33% of all open-angle glaucoma cases.

Low-tension glaucoma is thought to be partly related to the reduced flow of blood to the optic nerve. This causes the death of cells that transmit impulses from the retina to the brain. Additionally, people with normal-tension glaucoma often need to have IOPs lower than normal to prevent further sight loss.

• Angle Closure Glaucoma

Angle-closure affects nearly 500000 individuals in the U.S. Additionally; this disease has a tendency to be inherited and can afflict several people of the same family. It is statistically more common among Asians and far-sighted people.

People with angle-closure glaucoma tend to have a smaller than average anterior chamber. The angle formed where the iris and cornea meet is where the trabecular meshwork is located. For most individuals, this angle is around 45 degrees. The smaller this angle gets, the closer the trabecular meshwork is to the iris. As we get older, our eye lenses tend to grow which causes the aqueous humor to pass between the lens and iris with a lot of difficulties. This creates a fluid pressure build-up, and when this pressure becomes sufficiently high, an angle-closure glaucoma attack occurs.

• Acute Glaucoma

This is an angle-closure glaucoma type that occurs suddenly as opposed to POAG whose conditions are manifested gradually. The sudden rise in IOP can happen in just a matter of hours and is very painful. The eye will turn red as the cornea swells and the victim might begin seeing haloes around lights and have blurred vision.

Acute glaucoma is an emergency, and if treatment is delayed, loss of sight could happen. A lot of these sudden attacks tend to occur in darkened environments where pupils dilate an increase in size. When this happens, the contact between the iris and eye lens is at a maximum which further narrows the angle thus triggering an attack. Additionally, a pupil may dilate during a panic attack or when one is excited. This is why a lot of acute glaucoma attacks happen when an individual is stressed. Some medication such as antihistamines and antidepressants may also lead to an attack because they cause the pupil to dilate.

Being examined routinely is the best method for predicting one’s chances of having an acute attack. The examination checks typically for the width of the angle. An individual with narrow angles is advised immediately on their condition and given treatment.

• Pigmentary Glaucoma

This is another type inherited open-angle glaucoma that tends to occur more commonly in men. It typically starts during the 20s and 30s which makes the condition lethal because it could mean a lifetime of permanent blindness if not detected and treated early. It is more typical in individuals that are nearsighted. 

• Exfoliation Syndrome

Exfoliation is one of the most common causes of glaucoma and afflicts people around the globe. However, it statistically occurs more frequently among persons of European descent.

About 10% of people above 50 experience the deposition of whitish material that looks like dandruff on the lenses of their eyes. This exfoliation material may at times clog the trabecular meshwork thus causing an elevation in the intraocular pressure.

This syndrome may lead to both angle-closure and open-angle glaucoma; at times resulting in both types of glaucoma in the same person. Not all individuals with this condition develop glaucoma; however, they are six times more likely to develop glaucoma than someone without the exfoliation syndrome.

• Trauma-Related Glaucoma

An injury to the eye resulting from either a chemical burn, blow to the eye, or a penetrative injury could lead to the development of either acute or chronic glaucoma. This might be attributed to the mechanical disruption of the eye’s drainage system. Anyone who has suffered eye trauma is therefore advised to have eye examinations at regular intervals.

• Childhood Glaucoma

It is a rare form of glaucoma that occurs in 1 out of 10000 infants during birth. Its causes are related to diseases that cause abnormal increases in the IOP. This type of glaucoma is identified by the underdevelopment of the eye’s drainage area at birth. Its early symptoms include poor vision, light sensitivity, blinking, and tearing.

Treatment of pediatric glaucoma is done differently than adult glaucoma; infants will often require surgery. This invasive procedure aims to decrease fluid production within the eye or increase the discharge of fluid from the eye thereby reducing IOP.

Up to 90% of babies that receive surgical treatment promptly will have normal vision throughout their lifetime. 

Getting to know and understand the different forms of glaucoma is essential. It enables you to find out if at all you are at risk of getting this disease. As earlier mentioned, glaucoma often shows no signs until it is too late. It is, therefore, critical to not only know whether you are susceptible to glaucoma but to also have your eyes regularly checked. Get tested!

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