Common Types of Glaucoma and How They Affect Vision
Glaucoma is the name given to a collection of disorders that result in visual field loss due to a specific type of optic neuropathy (i.e. optic nerve disease or abnormalities). In glaucoma disease, Increased intraocular pressure is one of the numerous key risk factors for glaucoma development. However, no single pressure is symptomatic of the condition. At different eye pressures, the sensitivity of an individual's optic nerve and the retinal cells whose fibres make up the optic nerve called the ganglion cells to damage varies greatly. A normal eye pressure range is between 10 and 21 mm (0.4 and 0.82 inches) of mercury, although persons with pressures below 21 mm can develop glaucoma eye (normal-tension glaucoma, or low-tension glaucoma). Due to this very reason, glaucoma can also be referred to as eye pressure disease.
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Glaucoma Disease Symptoms
Symptoms of glaucoma in the eyes can be minimal to severe depending on the affected individual and it may increase and get worse with time when untreated.
Blind patches in your peripheral (side) or central vision, often in both eyes
Advanced phases of tunnel vision in the later stages of glaucoma eye disease
Headache that is severe
Pain in the eyes in the glaucoma eye disease is severe and will devoid you the focus in any kind of daily activities
Vomiting and nausea
Vision becomes hazy
Lights with halo effects are seen
Redness in the eyes
Causes of Glaucoma Disease
The exact cause is still unknown and as of writing the doctors and experts suggest that many factors contribute to glaucoma eye disease.
high or increased blood pressure
dilating eye drops
blocked or restricted drainage in the eye
drugs, such as corticosteroids
poor or diminished blood flow to the optic nerve
Types of Glaucoma Disease
The pace of aqueous humour generation by the ciliary body and the barrier to outflow through various channels influence a person's ocular pressure and eye pressure range. Primary open-angle glaucoma (POAG) and angle-closure glaucoma are the two main types of glaucoma. And even though the age group that is most affected by glaucoma is above 40 years of age the symptoms can start as early as birth due to conditions unknown and there have been many research studies that state that it can take years to actually define and distinguish its cause and treatment as it is associated with the optic nerve that is a part of the eye and the central nervous system as well.
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Risk Factors of Glaucoma
Age is a Factor- Glaucoma is more common in people over 60, according to the NEI which is a trustable source, and the risk of glaucoma increases slightly with each year of age. If you're African-American, your risk begins to rise at the age of 40.
Race and Ethnicity- African-Americans and people of African heritage are much more likely than Caucasians to acquire glaucoma. People of Asian ancestry are more vulnerable.
Problems with the Eyes- Increased eye pressure can be caused by chronic eye inflammation and weak corneas. Eye pressure can also rise as a result of physical injury or damage to the eye, such as being smacked in the eye.
History of the Family- Glaucoma can run in families in some cases. You have a higher chance of developing open-angle glaucoma if your parents or grandfather had it.
Medical Background- Glaucoma is more likely to develop in those who have diabetes, high blood pressure, or have heart disease.
Use of Certain Drugs- Long-term use of corticosteroids may raise your chances of acquiring secondary glaucoma.
Diagnosis of Glaucoma
Detailed Medical Background- Your doctor will want to know about your symptoms and whether you have a personal or family history of glaucoma. They'll also do a general health examination to see whether you have any other health issues that could be affecting your vision, such as diabetes or high blood pressure.
Tonometry is a test that measures how loud your voice is and the internal pressure of your eye is measured with this type of exam.
Test for Pachymetry- Glaucoma is more likely to occur in those with thin corneas. If your corneas are thinner than typical, a pachymetry test can notify your doctor.
Test of Perimetry- By assessing your peripheral, or side, vision and your central vision, this exam, also known as a visual field exam, can tell your doctor if glaucoma is impacting your eyesight.
Keeping an Eye on Your Optic Nerve- Your doctor may take images of your optic nerve to conduct a side-by-side comparison over time if they want to watch for progressive changes in your optic nerve.
Glaucoma Interesting Facts
The most common type of glaucoma, open-angle glaucoma, has almost no symptoms. Increased ocular pressure is rarely connected with pain. Peripheral or side vision loss is the first sign of vision loss. You may automatically adjust for this by tilting your head to the side, and you may not notice anything until your vision is severely impaired. Getting tested for glaucoma is the greatest approach to protect your vision. If you do suffer from glaucoma treatment should be from a professional and immediate.
Glaucoma is incurable, and vision loss is irreversible. It is feasible to prevent additional eyesight loss with medication and/or surgery. Because open-angle glaucoma is a chronic disease, it must be monitored for the rest of one's life.
Glaucoma can affect anybody, from infants to the elderly. Glaucoma is more common in older people, although it can also be passed down through the generations (approximately 1 out of every 10,000 babies born in the United States). Glaucoma can strike young adults as well. African Americans, in particular, are more vulnerable when they are younger.
If untreated, glaucoma can result in blindness. Unfortunately, roughly 10% of glaucoma patients who receive effective treatment nevertheless endure vision loss.
Conclusion
Most cases are caused by a build-up of the pressure in the eye when the cerebrospinal fluid is unable to drain properly. The nerve that connects the eye to the brain is then damaged as a result of the increased pressure (optic nerve). The slow progression of optic nerve damage causes little pain, and early sight loss is limited to the periphery of the visual field, only impacting central vision later on. In most cases, both eyes are damaged, albeit one may be more severely damaged than the other. Because glaucoma visual loss cannot be recovered, effective therapy can only prevent additional vision loss.
FAQs on What Is Glaucoma? Key Facts for Biology Students
1. What is glaucoma from a biological perspective?
From a biological perspective, glaucoma is a group of progressive eye diseases that cause damage to the optic nerve. This nerve is crucial as it transmits visual information from the retina to the brain. The damage is most often caused by an abnormally high pressure inside your eye, known as intraocular pressure (IOP), which gradually destroys the nerve fibres.
2. What is the primary biological mechanism that causes the pressure buildup in the eye?
The pressure buildup occurs due to an imbalance in the eye's fluid dynamics. The eye constantly produces a clear fluid called aqueous humour, which fills the front part of the eye. Normally, this fluid drains out through a spongy tissue called the trabecular meshwork. In glaucoma, either the eye produces too much fluid or the drainage system becomes blocked or inefficient, causing the fluid to accumulate and increase the intraocular pressure.
3. What are the two main types of glaucoma and their physiological differences?
The two main types are distinguished by how the fluid drainage is impaired:
Open-Angle Glaucoma: This is the most common type. The drainage angle formed by the cornea and iris remains open, but the trabecular meshwork becomes less efficient over time. The pressure in the eye increases gradually and painlessly.
Angle-Closure Glaucoma: This type occurs when the iris bulges forward, narrowing or blocking the drainage angle. This prevents aqueous humour from circulating out, leading to a sudden and rapid increase in eye pressure, which is often a medical emergency.
4. How does glaucoma specifically affect a person's field of vision?
Glaucoma typically damages the peripheral (side) vision first. As the optic nerve fibres are destroyed, blind spots develop in the outer visual field. A person might not notice this loss initially because the central vision remains clear. As the disease progresses, these blind spots grow larger, leading to a condition known as "tunnel vision," where only the central part of the vision remains. If left untreated, it can eventually lead to total blindness.
5. Why is glaucoma often called the "silent thief of sight"?
Glaucoma earns this name because its most common form, open-angle glaucoma, develops very slowly and without any obvious early symptoms like pain or immediate vision changes. The loss of peripheral vision is so gradual that the brain often compensates for the missing information. Consequently, a person may not be aware they have the disease until a significant portion of their optic nerve is already irreversibly damaged.
6. Is glaucoma a hereditary condition?
Yes, genetics play a significant role in the development of glaucoma, particularly open-angle glaucoma. If you have a close family member, such as a parent or sibling, with the disease, your risk of developing it is considerably higher. This is because certain genes influencing the development of the eye's drainage system and the resilience of the optic nerve can be inherited.
7. What is the difference between intraocular pressure (IOP) and glaucoma?
Intraocular pressure (IOP) is the measurement of the fluid pressure inside the eye, while glaucoma is the actual disease characterised by optic nerve damage. High IOP is a major risk factor for glaucoma, but they are not the same thing. It is possible to have high IOP without any nerve damage (a condition called ocular hypertension). Conversely, some people can develop glaucoma damage even with normal IOP levels (known as normal-tension glaucoma).
8. Can lifestyle factors influence the risk of developing glaucoma?
While primary risk factors like age, genetics, and ethnicity are non-modifiable, certain lifestyle and health conditions can influence the risk. Systemic conditions like diabetes and high blood pressure can affect blood flow to the optic nerve, potentially increasing susceptibility. Regular, moderate exercise can help lower IOP, while serious eye injuries can lead to secondary glaucoma. Therefore, maintaining overall cardiovascular health is considered beneficial.
