Glaucoma, Definition, Descriptions, Symptoms Risk Factors, Tonometry!
Glaucoma refers to a group of ocular pathologies that lead to the involvement of the optic nerve. The optic nerve is the nerve that transmits visual information from the eye to the brain.
In most cases, damage to the optic nerve is due to increased pressure in the eye, also called intraocular pressure.
Glaucoma is the second most common cause of blindness.
What causes the causes of glaucoma?
The front part of the eye is filled with a clear liquid called aqueous humor. The aqueous humor is present behind the colored part of the eye (the iris). The aqueous humor can "flow" from the eye through the channels in the front of the eye, in an area called "Angle of the anterior chamber" or simply the angle.
Any event, phenomenon, ... which slows or blocks the flow of aqueous humor out of the eye will cause pressure by the accumulation of aqueous humor in the eye. This pressure is called intraocular pressure. In most cases of glaucoma, this pressure is high and causes damage to the optic nerve.
What are the types of glaucoma?
- There are four categories of glaucoma
- Open-angle chronic glaucoma
- Acute angle-closure glaucoma
- Congenital glaucoma
- Secondary glaucoma
- Open-angle chronic glaucoma is the most common form of glaucoma
The cause of chronic open-angle glaucoma is unknown. An increase in intraocular pressure occurs slowly over time. The pressure pushes on the optic nerve.
Open-angle chronic glaucoma tends to be hereditary. The risk of developing open-angle chronic glaucoma is indeed higher if you have a parent or grandparent with chronic open-angle glaucoma. It should be noted that people of African descent are particularly at risk for this disease.
Closed-angle acute glaucoma occurs when the aqueous humor is abruptly
Acute angle-closure glaucoma causes a rapid, severe and painful increase in the pressure in the eye.
Acute closed-angle glaucoma is an emergency. Acute closed-angle glaucoma is very different from chronic open angle glaucoma
If you have acute angle-closure glaucoma in one eye, there are risks to the second eye. Your doctor may prescribe a preventive treatment
Note that dilating eye drops as well as certain drugs can trigger an acute crisis of acute angle-closure glaucoma
Congenital glaucoma is often diagnosed in babies
Congenital glaucoma is often hereditary.
Congenital glaucoma is present at birth
Congenital glaucoma is caused by abnormal development of the eyes
Secondary glaucoma
Secondary glaucoma can be caused by:
Drugs such as corticosteroids
Ocular diseases such as uveitis
Systemic diseases
A trauma
Most people have no symptoms for chronic open-angle glaucoma
Once vision loss occurs, the damage is already severe
There is a slow loss of side vision (peripheral vision)
Acute angle-closure glaucoma
Symptoms associated with acute angle-closure glaucoma may come and go at first or regularly worsen. The main symptoms of acute closed-angle glaucoma are:
Sudden and strong pain in one eye
Decreased vision or blurred vision
Nausea and vomiting
Halos of light in vision
Red eyes
A feeling of having your eyes swollen
Congenital glaucoma
Symptoms of congenital glaucoma can usually be diagnosed as soon as a child is a few months old. Symptoms of congenital glaucoma include:
The enlargement of one eye or both eyes
Red eyes
Sensitivity to light
A tear
Diagnosing glaucoma
A complete visual examination is necessary to diagnose glaucoma. For this purpose, eye drops may be given to dilate the patient's eyes. The ophthalmologist can then look inside the eye when the pupil is dilated.
A test called Tonometry is performed by an ophthalmologist to check and measure eye pressure.
However, the eye pressure keeps changing, evolving! An intraocular pressure may then be diagnosed as normal in some people with glaucoma. This is called normal pressure glaucoma. In this case, the doctor will need to perform further tests to confirm glaucoma.
Examinations for diagnosing glaucoma
A doctor will be able to diagnose glaucoma by performing certain tests, including:
Colonoscopy: The doctor looks at the eye with a special lens
An Imaging of the Optic Nerve, with a laser scan of the inside of the eyeExamination of the retina at the back of the eyeA Review at the Slit LampVisual acuityThe visual field of measurementTreatment of glaucomaThe goal of treating glaucoma is to reduce eye pressure. Treatment depends on the type of glaucoma the patient has.
If you have chronic open-angle glaucoma, ophthalmic drops are usually prescribed, most patients can be successfully dropped by eye drops. Pills to lower the pressure in the eye can also be prescribed.
Other glaucoma treatments may include:
A laser therapy called Iridotomy (see below)
Eye surgery if other treatments do not work
In the case of acute closed-angle glaucoma, this is a medical emergency, with blindness occurring within a few days after glaucoma, if not properly treated. Thus, for acute angle-closure glaucoma, it will generally be prescribed:
Eye Drops
Medicines for the reduction of ocular pressure administered orally and intravenously
Some people also need an emergency operation called Iridotomy. This procedure uses a laser to open a new path in the colored part of the eye. This relieves pressure and prevents further attack.
Congenital glaucoma is almost always treated by surgery and under general anesthesia, therefore without any pain.
For secondary glaucoma, treating the underlying disease can help your symptoms disappear. Other treatments may be necessary.
Prognosis for glaucoma
Chronic open-angle glaucoma can not be cured. However, you can manage symptoms by closely following your doctor's instructions. Regular checks are necessary to prevent blindness.
Acute angle-closure glaucoma is a medical emergency. You need immediate treatment to save your eye.
Babies with congenital glaucoma usually have good results when surgery is done early.
For secondary glaucoma, everything depends on the disease causing glaucoma.
Advice - Call your doctor
Call your doctor if you have severe eye pain or sudden loss of vision, especially the loss of peripheral vision.
Call a physician if you have any risk factors for glaucoma.
Prevention of Glaucoma
All adults should have a complete eye examination before age 40 or earlier if you have risk factors for glaucoma or other eye problems. You are part of a population at risk for a family history of chronic open-angle glaucoma.
Finally, if you are at high risk of acute angle glaucoma, talk to your doctor to plan an eye surgery to prevent an attack.
The information given on this site can not engage the author and are given for information purposes only. Also, consult a health care practitioner for any questions regarding glaucoma
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Chronic Closed-Angle Glaucoma
Who is concerned?
It is twice as common in women and occurs on small (hyperopia) eyes. The risk begins at age 35 and increases with age, due to the increase in the size of the lens.
The familial nature of this risk should make the family of an affected patient systematically consulted.
Mechanisms
The iris comes to rest against the trabecular (in red on the drawing) and obstructs it.
Two main mechanisms can cause this opposition: the pure pupillary block and the iris-plateau.
This opposition is progressive: the iris gradually sticks against the trabecular, preventing the aqueous humor from emerging. The intraocular pressure increases insidiously.
Symptoms
In rare cases, the patient complains of colored halos at night, or eye discomfort sometimes accompanied by headaches at night. The peculiarity of these signs is that they occur when the low lighting causes an iris dilation (mydriasis). This mydriasis increases the green bulge and therefore the opposition of the iris on the trabeculae.
But most often these glaucomas, which are called closed-angle chronicles, are totally painless and insidious until the visual field is altered so much that the patient notices it, in the same way as for glaucoma (See the symptoms page).
Specific treatment: Laser iridotomy.
If the risk of the opposition of the iris to the trabecular is considerable, and especially if there are places where the iris adheres to the trabecula, the first treatment consists of making a small hole in the periphery of the trabecular, iris. The mechanism of action of the Laser is explained here.
It is the best preventive treatment for glaucoma by closing the angle: when the laser is practiced before the occurrence of true glaucoma, it is often enough (except in the case of the iris-plateau syndrome), but the lifetime surveillance necessary.
When glaucomatous involvement is present, complementary treatment is generally necessary.
When the iris is glued to a too large portion of trabeculae, the Laser must immediately give way to the surgery.
Closed-angle chronic glaucoma is more often than open-angle glaucoma difficult to balance by medical treatment alone. Laser treatment with trabeculoplasty is generally impossible due to the iris being placed on the trabeculae.
The surgery is identical to that performed in cases of glaucoma with the open angle but sometimes more difficult. When the lens is voluminous, its extraction, accompanied or not by a filtering surgery, can be proposed.
(Loss of vision)
About this condition
Description
Causes
Symptoms and Complications
Diagnostic
Treatment and Prevention
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Description
Glaucoma is a progressive disorder of the eye in which the cells of the optic nerve are damaged by excessive pressure of the liquid contained in the eyeball. This is the second leading cause of blindness in North America after diabetes.
Glaucoma often has a family component. There are several types of glaucoma, each of which depends on different pathological processes and tends to appear in different racial groups. Overall, people of African descent are more prone to glaucoma than Caucasians.
Other risk factors for glaucoma include age (over 40 years), elevated intraocular pressure (IOP: pressure inside the eye), myopia, diabetes, High blood pressure and a history of eye injury.
Causes
The anterior part of the eye is a D-shaped cavity in which the crystalline lens and the iris (colored part of the eye) from the rectilinear wall, while the cornea (the surface of the eye) forms the curved wall. A gland behind the upper eyelid fills this cavity with a clear fluid (aqueous mood), which supplies the front of the eye with oxygen and nutrients and keeps it inflated. A constant supply of liquid is produced; It flows through small openings located behind the lower eyelid, called the trabecular network.
In the case of glaucoma, the fluid is produced normally, but the trabecular network can not eliminate it, because of obstruction or for some other reason. The pressure of the fluid increases in the eye, which compresses the optic nerve (the nerve that connects the eye to the brain). The supply of blood to the nerve cells is then gradually reduced, and the cells eventually die. The external nerves are affected first and the vision is usually lost, starting from the extremities, leaving only a "tunnel vision" and progressively causing blindness. Often people do not notice this phenomenon, which is usually not accompanied by pain, and glaucoma can be quite advanced when detected. According to the Glaucoma Foundation of the United States, only one person in two suffering from this disease is aware of this.
The types of glaucoma are classified according to the obstruction which prevents the drainage of the liquid:
Open-angle primary glaucoma is the most common form of glaucoma in North America and affects about 1 in 100 people. People of African descent are particularly sensitive to glaucoma. The disease usually appears in people over 50 years of age. The trabecular network appears normal to examination but does poorly drainage. Some researchers believe that cell efficiency is reduced due to aging; Others believe that the defect comes from a disturbance under the eye or is explained by another cause. In any case, the pressure builds up and the optic nerve begins to fail. Blind spots appear in the peripheral vision, then in the central region of the sight. This damage can not be repaired. Primary angle glaucoma is progressively worsened if left untreated.
Closed-angle glaucoma is more common in people of Asian or Inuit ancestry, in women and in hyperopia. The condition may be chronic or intermittent. As the trabecular network is situated at an angle to the D between the iris and the cornea, everything that makes the iris swell or pushes it back forward can close this angle, which blocks the network. Some diseases, such as diabetes or uveitis (an inflammatory condition of the eye), can push the iris forward. Aging also tends to thicken the lens and the iris, obstructing the flow of fluid between the anterior cavity and the posterior cavity of the eye. The pressure accumulates in the posterior cavity (the main part of the eyeball), which pushes the iris forward and closes the trabecular network.
In cases of normal pressure glaucoma, the eye pressure is within the normal limits, but the optic nerve is still damaged. It appears that a poor perfusion of the optic nerve makes it more vulnerable. A slightly above average pressure can then damage it.
Pigmentary glaucoma mainly affects young myopic patients. The iris, which is concave in myopia, rubs against the pigment layer which gives the eye its color. Fragments of pigment detach and obstruct the trabecular network, thus increasing the pressure. Exfoliation syndrome, which is more common in Caucasians after age 50, is a similar disorder. Fragments of white matter appear on the lens before falling and obstructing the network. Exfoliation syndrome does not necessarily result in glaucoma but increases the risk of developing the disease by six times.
Traumatic glaucoma is the result of an eye injury that often occurs many years after the event.
The biggest difficulty with glaucoma comes from the absence of symptoms because you can not feel the pressure of the eye. Only a few people experience headaches or find that they have red eyes or blurred vision. If eye exams are not performed regularly, the first symptom that may appear is the presence of permanent "holes" in the field of vision. Non-treatment of glaucoma often leads to blindness.
People with severe eye pain, red eyes, and vision problems may have a closed angle glaucoma attack. This is a serious complication in which the iris swells or moves forward and completely obstructs the trabecular network. People who are prone to closed-angle glaucoma are more prone to acute attack when they are in the dark, as the pupil opens when there is the little light, which reduces the angle. During a light attack, halos may appear around the objects and the view may be slightly blurred, but without causing pain. Extreme pain and swelling with reddening of the eyes indicate a medical emergency. Blindness can occur rapidly if the disorder is not treated.
Diagnostic
The first thing the doctor should check is the internal pressure of the eye. A pulsed air tonometer makes it possible to measure it without coming into contact with the eye. The doctor can also examine the eye through the transparent pupil, using an ophthalmoscope. This examination is essential since normal pressure glaucoma can not be diagnosed by eye pressure.
The first damage caused by glaucoma can be detected using an assessment of the visual fields. The person must then indicate the presence of flashing lights that are installed at the end of the field of vision. This examination is often carried out using a computer.
Treatment and Prevention
Various medications help to relieve eye pressure and prevent lesions. Most are administered as eye drops. Beta-blockers (eg betaxolol *, levobunolol, timolol), alpha-2 agonists (eg brimonidine) and carbonic anhydrase inhibitors (eg dorzolamide, brinzolamide) slow production Of the eye fluid (aqueous humor) whereas prostaglandin analogs (eg latanoprost, travoprost, bimatoprost) and myopic (pupil-contracting drugs) such as pilocarpine improve drainage. However, these medications should be taken for the rest of their lives, and patients with glaucoma often prefer surgery or laser treatment.
The most common procedure is laser trabeculoplasty. This operation is performed for 15 minutes in an outpatient clinic and does not cause any pain. The laser light does not cause any damage as it passes through the surface of the eye, its energy being concentrated on the trabecular network, reducing its volume and releasing the openings. After this operation, the patient can often abandon his medication against glaucoma. There are also other possible surgical procedures if this maneuver fails.
The most common procedure is laser trabeculoplasty. This operation is performed for 15 minutes in an outpatient clinic and does not cause any pain. The laser light does not cause any damage as it passes through the surface of the eye, its energy being concentrated on the trabecular network, reducing its volume and releasing the openings. After this operation, the patient can often abandon his medication against glaucoma. There are also other possible surgical procedures if this maneuver fails.
If glaucoma is treated early, it is possible to minimize or prevent loss of vision. Since glaucoma is often asymptomatic, it is important to periodically examine the eyes, especially in the presence of the following risk factors:
- A family history of glaucoma;
- An African origin;
- Myopia;
- Anterior injury to the eye;
- High blood pressure;
- Diabetes;
Prolonged exposure to prednisone, cortisone or other steroids.
If you are between 20 and 64 years old, an eye examination should be performed every 1 to 2 years. After 65 years, your eyes should be examined every year. However, if you present any of the risk factors you should take an exam as often as a professional eye recommends.
GLAUCOMA
What is Glaucoma?
Glaucoma is an ocular disease in which the pressure inside the eye increases to the point of damaging the optic nerve. The increase in pressure is due to a problem of production, flow or drainage of the liquid normally produced in the eye. Glaucoma is one of the leading causes of blindness in Canada.
What causes glaucoma?
The exact cause is not known. For whatever reason, there is the overproduction of liquid or blockage of passages where the liquid usually escapes from the eye. The pressure thus increases inside the eye and can easily damage the nerve fibers of the optic nerve and the blood vessels. The increase in pressure may also come from an injury, infection or tumor within or around the eye.
Who is affected by glaucoma?
Glaucoma occurs more often after age 40 and the disease appears to be hereditary in several cases. Open-angle primary glaucoma causes damage at a younger age and makes blindness appear much more rapidly. People who have diabetes, hypertension or eye damage are at greater risk of developing glaucoma. Regular optometric examinations are important at any age to assess the risk of this disease.
Why does glaucoma affect vision?
The optic nerve, which is located at the back of the eye, transmits visual information to the brain. When the fibers of this nerve are damaged, the amount and quality of information sent to the brain diminish, leading to loss of vision.
Will glaucoma blind me?
If diagnosed early, glaucoma can be controlled and thus result in almost no loss of vision. Otherwise, peripheral and central vision will be lost and almost complete blindness may occur.
How do I know if I have glaucoma?
Primary glaucoma with open angle appears painlessly and slowly and gradually. There are no warning signs or symptoms. It can gradually destroy your vision without you knowing it. Acute closed-angle glaucoma is accompanied by symptoms, such as severe pain in the affected eye, redness in the eyes, blurred vision, halos around the lights, and even nausea.
How is glaucoma diagnosed?
A complete assessment of eye health is often the only way to detect glaucoma. Your optometrist includes in your exam a simple, painless procedure called tonometry, which is used to measure the pressure inside the eye. Your optometrist will also examine the condition of the optic nerve and measure your field of vision.
How is glaucoma treated?
Ophthalmic drops and/or surgery will usually help preserve the rest of your vision. Vision loss due to glaucoma can not be recovered. This is why regular preventive examinations are so important.
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