yulius hermanto
Glaucoma: A Sight Thief
Introduction
During my clinical rotation in medical education at Opthalmology Department, I found a lot of interesting eye cases. Thus, i couldn't forget for the rest of my life.
One of those cases is glaucoma. What is Glaucoma? Some people say it as sight thief, thus decreasing your vision without any symptoms, and when you are aware of it, it's been too late.
Approximately 2.8 million Americans have been diagnosed with glaucoma. Another 2.8 million may be living with the disease and not
yet know it. Worldwide, it is estimated that about 66.8 million people have visual impairment from glaucoma, with nearly 6.7 million suffering from bilateral blindness.
It is likely that only 50% of people living with glaucoma are actually aware they have the disease.
Glaucoma is group of eye disorders that have few symptoms in their early stages, but eventually leads to damage of the optic nerve (the bundle of nerve fibers that carries information from the eye to the brain), which can then lead to loss of side vision or complete blindness.
Some of the cases that i found during my clerkship, are advanced stage or almost blind, only pinhole vision left, while the patient is still teenager.
Blindness that is caused by glaucoma is different with cataract, in glaucoma the blindness is permanent, while in cataract can be cured by cataract extraction.
Thus early detection of glaucoma is important to prevent or slow down the ongoing nerve damaged.
Aqueous Humor and Glaucomatous Damaged
Most, but not all, forms of glaucoma are characterized by high eye (intraocular) pressure. Intraocular pressure remains normal when some of the fluid (aqueous humor) produced by the eye’s ciliary body flows out freely (follow blue arrow). Aqueous humor flows from the ciliary body into the anterior chamber, out through a spongy tissue at the front of the eye called the trabecular meshwork and into a drainage canal (dark blue region next to the trabecular meshwork). In open-angle glaucoma, fluid does not flow freely through the trabecular meshwork, causing an increase in intraocular pressure, damage to the optic nerve and vision loss.
Seems like Aqueous humor is the source of the problems, does it has a function for our eyes? It's maybe become question for most of glaucoma patients since they don't get enough information.
Aqueous humor is secreted by ciliary body in order to supply nutrition for avascular tissues in our eyes such as cornea and lens. Besides that aqueous humor has role in order to maintain eye shape, and prevent eye collapse or pthisis bulbi. Thus aqueous humor is important to maintain function of our eye as vision organ.
But, in glaucoma patients, there are a problems related to aqueous humor circulation, mostly at excretory part thus causes the increased of intraocular pressure.
The increased of intraocular pressure spread diffusely according to Pascal's Law. But in eye, there is a weaker part or more sensitive tissue that is optic nerve. The increased of pressure damaged the nerve directly or indirectly. And when optic nerve is damaged, the damaged is irreversible.
Types of Glaucoma
Open-Angle Glaucoma
Open-angle glaucoma, the most common form of glaucoma, accounting for at least 90% of all glaucoma cases:
- Is caused by the slow clogging of the drainage canals, resulting in increased eye pressure
- Has a wide and open angle between the iris and cornea
- Develops slowly and is a lifelong condition
- Has symptoms and damage that are not noticed.
“Open-angle” means that the angle where the iris meets the cornea is as wide and open as it should be. Open-angle glaucoma is also called primary or chronic glaucoma.
Angle-Closure Glaucoma
It is also called acute glaucoma or narrow-angle glaucoma. Unlike open-angle glaucoma, angle-closure glaucoma is a result of the angle between the iris and cornea closing.
Angle-closure glaucoma comes in two forms: acute or chronic.
Acute angle-closure glaucoma occurs when the normal flow of aqueous humor between the iris and the lens is suddenly blocked. Symptoms may include severe pain, nausea, vomiting, blurred vision and a rainbow halo appearing around lights. Acute angle-closure glaucoma is a medical emergency that must be treated immediately or blindness can result in one or two days.
Chronic angle-closure glaucoma progresses slowly and can produce damage without symptoms, similar to open-angle glaucoma.
Normal-Tension Glaucoma (NTG)
Also called low-tension or normal-pressure glaucoma. In normal-tension glaucoma the optic nerve is damaged even though the eye pressure is not very high. We still don't know why some people’s optic nerves are damaged even though they have almost normal pressure levels.
There are also several other forms of glaucoma, including normal-tension, congenital, juvenile and secondary. Secondary glaucoma can be open-angle or closed-angle and results from another medical condition in the eye or body. Examples of secondary glaucoma include pseudoexfoliation syndrome, neovascular, pigmentary, and iridocorneal endothelial syndrome (ICE syndrome).
Risk Factors
Strong risk factors for open-angle glaucoma include:
- High eye pressure
- Family history of glaucoma
- Age 40 and older for African Americans
- Age 60 and older for the general population
- Thin cornea
- Suspicious optic nerve appearance with increased cupping (size of cup, the space at the center of optic nerve, is larger than normal)
Potential risk factors for open-angle glaucoma include:
- High myopia (very severe nearsightedness)
- Diabetes
- Eye surgery or injury
- High blood pressure
- Use of corticosteroids (for example, eye drops, pills, inhalers and creams)
Glaucoma Evaluation
Eye doctors use several tests to detect glaucoma including: visual acuity test, visual field test, dilated eye exam, tonometry, pachymetry, ophthalmoscopy, gonioscopy and optic nerve imaging.
Individuals at high risk for glaucoma should have a dilated pupil eye examination, including a visual field test, every 1-2 years or as directed by a doctor.
Currently, there is no cure for glaucoma; however, through early diagnosis and treatment, the disease can be controlled before vision loss or blindness occurs. Treatments for open-angle glaucoma include: medications, usually eye drops, to help eye fluid drain more effectively or lessen fluid production; laser surgery; and conventional surgery.
New treatment research is focused on lowering pressure inside the eye, finding medications to protect and preserve the optic nerve from the damage that causes vision loss, and the role of genetic factors.
During my clinical rotation in medical education at Opthalmology Department, I found a lot of interesting eye cases. Thus, i couldn't forget for the rest of my life.
One of those cases is glaucoma. What is Glaucoma? Some people say it as sight thief, thus decreasing your vision without any symptoms, and when you are aware of it, it's been too late.
Approximately 2.8 million Americans have been diagnosed with glaucoma. Another 2.8 million may be living with the disease and not
yet know it. Worldwide, it is estimated that about 66.8 million people have visual impairment from glaucoma, with nearly 6.7 million suffering from bilateral blindness.
Glaucoma is group of eye disorders that have few symptoms in their early stages, but eventually leads to damage of the optic nerve (the bundle of nerve fibers that carries information from the eye to the brain), which can then lead to loss of side vision or complete blindness.
Some of the cases that i found during my clerkship, are advanced stage or almost blind, only pinhole vision left, while the patient is still teenager.
Blindness that is caused by glaucoma is different with cataract, in glaucoma the blindness is permanent, while in cataract can be cured by cataract extraction.
Thus early detection of glaucoma is important to prevent or slow down the ongoing nerve damaged.
Glaucoma, Vision Stealer
Most, but not all, forms of glaucoma are characterized by high eye (intraocular) pressure. Intraocular pressure remains normal when some of the fluid (aqueous humor) produced by the eye’s ciliary body flows out freely (follow blue arrow). Aqueous humor flows from the ciliary body into the anterior chamber, out through a spongy tissue at the front of the eye called the trabecular meshwork and into a drainage canal (dark blue region next to the trabecular meshwork). In open-angle glaucoma, fluid does not flow freely through the trabecular meshwork, causing an increase in intraocular pressure, damage to the optic nerve and vision loss.
Seems like Aqueous humor is the source of the problems, does it has a function for our eyes? It's maybe become question for most of glaucoma patients since they don't get enough information.
Aqueous humor is secreted by ciliary body in order to supply nutrition for avascular tissues in our eyes such as cornea and lens. Besides that aqueous humor has role in order to maintain eye shape, and prevent eye collapse or pthisis bulbi. Thus aqueous humor is important to maintain function of our eye as vision organ.
But, in glaucoma patients, there are a problems related to aqueous humor circulation, mostly at excretory part thus causes the increased of intraocular pressure.
The increased of intraocular pressure spread diffusely according to Pascal's Law. But in eye, there is a weaker part or more sensitive tissue that is optic nerve. The increased of pressure damaged the nerve directly or indirectly. And when optic nerve is damaged, the damaged is irreversible.
Types of Glaucoma
Open-Angle Glaucoma
Open-angle glaucoma, the most common form of glaucoma, accounting for at least 90% of all glaucoma cases:
- Is caused by the slow clogging of the drainage canals, resulting in increased eye pressure
- Has a wide and open angle between the iris and cornea
- Develops slowly and is a lifelong condition
- Has symptoms and damage that are not noticed.
“Open-angle” means that the angle where the iris meets the cornea is as wide and open as it should be. Open-angle glaucoma is also called primary or chronic glaucoma.
Angle-Closure Glaucoma
It is also called acute glaucoma or narrow-angle glaucoma. Unlike open-angle glaucoma, angle-closure glaucoma is a result of the angle between the iris and cornea closing.
Angle-closure glaucoma comes in two forms: acute or chronic.
Acute angle-closure glaucoma occurs when the normal flow of aqueous humor between the iris and the lens is suddenly blocked. Symptoms may include severe pain, nausea, vomiting, blurred vision and a rainbow halo appearing around lights. Acute angle-closure glaucoma is a medical emergency that must be treated immediately or blindness can result in one or two days.
Chronic angle-closure glaucoma progresses slowly and can produce damage without symptoms, similar to open-angle glaucoma.
Normal-Tension Glaucoma (NTG)
Also called low-tension or normal-pressure glaucoma. In normal-tension glaucoma the optic nerve is damaged even though the eye pressure is not very high. We still don't know why some people’s optic nerves are damaged even though they have almost normal pressure levels.
There are also several other forms of glaucoma, including normal-tension, congenital, juvenile and secondary. Secondary glaucoma can be open-angle or closed-angle and results from another medical condition in the eye or body. Examples of secondary glaucoma include pseudoexfoliation syndrome, neovascular, pigmentary, and iridocorneal endothelial syndrome (ICE syndrome).
Glaucoma Vision
Risk Factors
Strong risk factors for open-angle glaucoma include:
- High eye pressure
- Family history of glaucoma
- Age 40 and older for African Americans
- Age 60 and older for the general population
- Thin cornea
- Suspicious optic nerve appearance with increased cupping (size of cup, the space at the center of optic nerve, is larger than normal)
Potential risk factors for open-angle glaucoma include:
- High myopia (very severe nearsightedness)
- Diabetes
- Eye surgery or injury
- High blood pressure
- Use of corticosteroids (for example, eye drops, pills, inhalers and creams)
Glaucoma Evaluation
Eye doctors use several tests to detect glaucoma including: visual acuity test, visual field test, dilated eye exam, tonometry, pachymetry, ophthalmoscopy, gonioscopy and optic nerve imaging.
Individuals at high risk for glaucoma should have a dilated pupil eye examination, including a visual field test, every 1-2 years or as directed by a doctor.
Currently, there is no cure for glaucoma; however, through early diagnosis and treatment, the disease can be controlled before vision loss or blindness occurs. Treatments for open-angle glaucoma include: medications, usually eye drops, to help eye fluid drain more effectively or lessen fluid production; laser surgery; and conventional surgery.
New treatment research is focused on lowering pressure inside the eye, finding medications to protect and preserve the optic nerve from the damage that causes vision loss, and the role of genetic factors.
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Actually i dunno how to describe it in words, maybe it isn't that scary.
Anyway it is important for us to increased awareness of glaucoma.