GLAUCOMA - The silent thief of sight
Although, the human eye sees and captures images from the outside world, however, it requires interpretation by the brain for us to make cognitive meaning out of what we see, and this can be achieved through the help of a nerve that connects the eye to the brain, the optic nerve. The optic nerve is one structure in the human eye that is very important when it comes to glaucoma.
Glaucoma is a group of eye diseases that is characterized by an irreversible loss of vision, due to damages in the optic nerve. Glaucoma is one of the leading causes of blindness for elderly age group (>60 years), it can also occur at any age. The symptoms are usually slow but progressive, and unnoticeable until it has caused a considerable amount of damage. The only way to find out if you have glaucoma is via a comprehensive eye exam, which is advised annually for early detection and early treatment.
Glaucoma is commonly cause by fluid (known as the aqueous humour) building up in the anterior part of the eye, leading to increased eye pressure on the optic nerve. This high pressure that is long standing is dangerous and can lead to optic nerve damage and eventually blindness.
Elevated intraocular pressure can also be due to an obstruction in the flow of aqueous humour which can also result in glaucoma.
The following are other things that may put one at risk of having glaucoma:
- Family history: if anyone in the family has glaucoma, it is advisable every member goes for an eye check-up as they are highly predisposed to having it too.
- Positive history of diabetes mellitus or/and systemic hypertension.
- Trauma, burn or chemical injury to the eye that compromise the drainage of the aqueous humour.
- Chronic eye infection or inflammation (uveitis).
- Retina diseases that affect the iris (the coloured part of the eye) may also cause glaucoma.
The fluid at the anterior part of the eye has its own production and drainage system, that helps to keep the pressure of the eye balanced.
The most common types of glaucoma are from problems with the drainage angle of the aqueous humour. Other types of glaucoma can result from a different health condition or injury that causes an increase in the intraocular pressure.
Types basically include:
- Acute Angle- closure Glaucoma: It is a less common type of glaucoma that occurs when the fluid pressure inside the eye rises suddenly and progresses rapidly, as a result of a blockage in the drainage angle. This type of glaucoma is associated with severe eye pain, redness and reduced or blurry It is a serious condition that is considered an ocular emergency.
- Open Angle Glaucoma: This is a type of glaucoma where the drainage angle is usually found opened. It is often associated with a problem in the drainage rate, which in turn exerts pressure in the eye affected. This type of glaucoma is the most common that has been reported so far.
- Secondary Glaucoma: This type of glaucoma occurs due to the presence of an underlying medical condition that causes the increase in eye pressure, such as: eye injury, Inflammation, diabetes, or as a side effect from use/overtime use of certain medications. It can be either the open-angle or angle-closure type of glaucoma and may occur in one or both eyes.
- Normal Tension Glaucoma: Normal-tension glaucoma (also known as low-tension glaucoma or normal-pressure glaucoma), is damage to the optic nerve not caused by increased eye pressure. People diagnosed with this type of glaucoma have ‘relative’ normal eye pressure, but with other clinical signs of glaucoma present. It is currently considered a form of open-angle glaucoma.
- Congenital glaucoma: This is a rare condition, that occurs as a result of an abnormal formation of a child's drainage canal during the embryological stage of development in the womb. It is usually diagnosed during the first year of life and is often hereditary.
At first, glaucoma doesn’t usually have any symptoms. That’s why half of people with glaucoma don’t even know they have it. Hence the nickname "silent thief of sight"
Over time, you may slowly lose vision, usually starting with your side (peripheral) vision — especially the part of your vision that’s closest to your nose. Because it happens so slowly, many people can’t tell that their vision is changing at first, but as the disease progresses and gets worse, you may start to notice that you can’t see things off to the side anymore. Without treatment, glaucoma can eventually lead to an irreversible blindness.
Depending on the cause of the glaucoma, symptoms vary from person to person. However, some of the symptoms one may experience with glaucoma include:
- Blurry vision/ vision loss.
- Redness, etc.
To diagnose glaucoma complete eye examination is recommended by an Optometrist or an Ophthalmologist. Your eye doctor may recommend one or more of these diagnostic tests and procedures as part of an evaluation.
Common tests & procedures
- Ophthalmoscopy: To objectively assess the optic nerve and evaluate for any sign of glaucoma.
- Tonometry: This gives a measurement of the eye’s pressure.
- Perimetry: This procedure helps to determine the extent of vision of the patient and detects if there is any area of vision loss, using a Central Visual Field Analyzer.
- Pachymetry: To determine the thickness of the cornea (the front surface of the eye where the aqueous humour baths posteriorly).
- Gonioscopy: To tell whether an open-angle or a closed-angle is gla
As earlier established, the damage caused by glaucoma is irreversible. Treatment and regular eye check-ups can however, help slow down it's progression or prevent further loss of vision, especially if diagnosed early.
Treatment aims at reducing the intraocular pressure and preventing further damage to the optic nerve. Reduction of intraocular pressure can be done either by increasing the drainage of the aqueous humour or by reducing its production through medications. Depending on one's situation, options may include:
- Prescription eyedrops.
- Oral medications.
- Laser treatment or surgery.
- A combination of any of these.
- Maintain a healthy weight by exercising regularly by being cautious of one's diet. It is advisable to take more fruits and vegetables.
- Don’t smoke or drink too much of alcohol, such habits could predispose one to some harmful eye conditions.
- Keep your blood pressure by reducing avoidable stress.
- Some research studies suggest that high amounts of caffeine may increase eye pressure, hence, control caffeine intake to moderate levels.
- Try to exercise daily by doing physical activities such as walking, running or getting one busy with a physical task at home like lawn mowing, etc.
- Prevent over-exposure to sunlight by wearing sunglasses and hats when you’re outdoors.
- Don't wait for you to have any complaint before you go and check your eyes. Make it a habit to get a regular comprehensive eye examination at least once in a year.