Glaucoma – everything you need to know about
Glaucoma is the second most common cause of blindness worldwide 1 . According to the World Health Organization, around 4.5 million people worldwide suffer from blindness caused by glaucoma. This number is expected to grow to 11.2 million people by 2020. That’s an increase of 149%, or an additional 6.7 million people who are at risk of losing their sight from this “silent, blinding disease” without even knowing it. 2 BETTER VISION explains what you should know about this group of eye diseases, eye pressure and the causes, risk factors, screening methods and treatment associated with glaucoma.
- Table of Contents
- What is glaucoma?
- How does glaucoma affect vision?
- Glaucoma prevention
- Investigation of glaucoma
- Treatment of glaucoma
What is glaucoma?
Glaucoma is a complex disease with many forms. However, in short, it can be defined as damage to the nerve connecting the eye to the brain (optic nerve), usually caused by pressure in the eye (intraocular pressure), which affects your field of vision and vision.
The risk of developing glaucoma is six times higher if you are over 60.
To better understand how the optic nerve works, let’s describe how the eye works:
The ciliary body produces a clear, watery fluid called aqueous humor in the anterior chamber. This fluid nourishes various parts of the eye, including the lens, cornea, and eye tissues. The aqueous humor is then drained from the eye through a spongy network called the trabecular meshwork through Schlemm’s canal into the blood vessels.
Glaucoma most commonly affects Schlemm’s canal or trabecular meshwork and thus prevents the aqueous humor from draining normally from the eye. We can compare it to a concrete dam with a blocked overflow – if the dam is constantly full of water that cannot drain, the pressure will build up and the dam will eventually burst. A similar principle applies when there is a blockage of Schlemm’s canal or trabecular meshwork. A buildup of aqueous humor will occur, which will affect the pressure in the eye, which will in turn damage the optic nerve and thus affect your vision.
Development of glaucoma
A healthy eye
Eye affected by glaucoma: Pressure increases in the eye causing damage to the optic nerve.
There are two categories of glaucoma, angle-closure glaucoma and open-angle glaucoma. Each category is defined by the position of the lens and iris in relation to the trabecular meshwork 3 . This position determines how the aqueous humor is drained from the eye or not.
Angle-closure glaucoma
In angle-closure glaucoma, the angle between the iris and cornea is either narrowed or blocked. Otherwise, the trabecular meshwork will be damaged, which will cause the accumulation of aqueous humor and a sudden increase in intraocular pressure. This condition leads to severe eye pain and requires immediate medical care to prevent blindness.
In the case of primary angle-closure glaucoma, the increase in pressure in the eye has no identifiable cause and can only occur because of the way the eye is segmented. If there is a secondary cause, such as a primary disease, injury, inflammation, or diabetes causing a sudden increase in pressure in the eye, it is secondary angle-closure glaucoma.
Open angle glaucoma
In open-angle glaucoma, the aqueous humor drainage angle between the iris and the cornea is wide and open, but there is a slow blockage of the drainage channels. Chamber water passes through the trabecular meshwork too slowly and is not properly drained. This constantly increases the pressure in the eye, which can damage the optic nerve and lead to blindness. You don’t notice the symptoms right away, they often go completely unnoticed.
Open-angle glaucoma is among the most common forms of this type of eye disease and forms, according to the foundation Glaucoma Research Foundation at least 90% of cases of glaucoma.
As with angle-closure glaucoma, open-angle glaucoma can be divided into primary and secondary:
Primary open-angle glaucoma (POAG)
This category includes forms of glaucoma in which there is a slow blockage and there is no clearly identifiable secondary cause of the blockage.
Risk factors for POAG include:
- increased pressure in the eye
- age (60 and over)
- genetic factors, eg family history of glaucoma
- ethnicity – people of Hispanic or African descent have a higher risk of developing POAG 4
- POAG is at greater risk for people suffering from short-sightedness (myopia) 5
- diabetes
- taking certain medications
- sleep apnea
Secondary open-angle glaucoma (SOAG)
In this category, the slow blockage of the drainage channels has a clear cause.
Secondary factors that can lead to SOAG include:
- operation
- trauma
- taking medication, eg cortisone
- congenital factors that are present at or after conception
- medical conditions such as pseudoexfoliation (abnormal accumulation of protein in the eye) and pigment dispersion syndrome (causes pigmentary glaucoma)
- inflammatory disorders of the eye (uveitis)
- mechanical blockage caused by increasing lens thickness (phacomorphic glaucoma)
How does glaucoma affect vision?
Aside from the sudden increase in eye pressure and extreme pain associated with angle-closure glaucoma, glaucoma is often not noticed until the optic nerve and retina have been damaged. Patients suffering from primary open-angle glaucoma rarely experience visual symptoms, especially at the onset of the disease. 6
Glaucoma affects peripheral (edge) vision, and noticeable symptoms include tunnel vision, a narrowed field of vision, colored rings when looking at bright light sources, and a general loss of visual acuity and contrast perception. Sometimes glaucoma even causes parts of the field of vision to disappear. It can affect one or both eyes and, if left untreated, can lead to total vision loss.
Normal vision
Vision affected by glaucoma
Glaucoma can be described as a silent disease because even when vision is impaired, the brain is able to cope with the changing circumstances and fill in the missing information so that the affected person does not notice the symptoms.
Prevention of green cloud
Glaucoma cannot be prevented, but blindness can be prevented if you are aware of the risk factors associated with the condition.
If you are at increased risk of developing glaucoma, for example because of your ethnicity, diabetes, family history or age, it is important to have regular glaucoma screenings.
Individual lifestyle factors may also play a role. The risk of developing glaucoma can be effectively reduced by preventing high blood pressure, managing sleep apnea, and following cortisone treatment with the help of a doctor.
Warning signs to look out for include:
- chronic headaches
- blurred vision
- pain behind the eye
- teary eyes
If you experience any or more of these symptoms, visit your nearest optician or eye doctor and ask for a glaucoma test.
How often should you go for an intraocular pressure test?
Everyone should attend regularly eye examinations, including a glaucoma screening, at least once every two years, especially if you are 40 or older. The risk of glaucoma increases even more once you reach the age of 60. Discuss the frequency of screenings with your optician.
If you wear glasses, your optician will probably have a glaucoma test at each eye test visit. If you do not have vision problems, you may not receive a regular screening. Keep this in mind and try to visit an optician near you which will screen you even if you don’t wear glasses.
If you have diabetes, are over 60, or have someone in your family with glaucoma, you should be screened once a year.
What does a glaucoma screening involve?
There are several ways to test for the presence of green turbidity. Your optician may combine these examinations.
Tonometry
This is the most common examination that measures intraocular pressure. A device called a tonometer releases a small burst of air into the eye and measures the pressure in the eye. It is not a painful or invasive examination and takes only a few minutes. However, you may find it a bit uncomfortable.
Using the values measured by the tonometer, the optician will then recommend the next procedure. Although eye pressure is unique to each of us, according to the foundation Glaucoma Research Foundation is the range of normal pressure usually between 12 to 22 mm Hg. However, most cases of glaucoma are diagnosed at levels above 20 mm Hg.
It is important to remember that tonometer results give a rough indication of your intraocular pressure at any given moment. Like blood pressure, intraocular pressure can vary between measurements.
Your optician will provide you with specific information about the measured values and, if the measured values are unusual, will refer you to an eye doctor.
The ZEISS VISUPLAN 500 tonometer enables an easy examination of the intraocular pressure using a gentle air discharge – non-contact and without the need to numb the eye.
Fundoscopy and fundus photography
Before the exam, eye drops are applied to dilate the pupils, and then the eyes are examined with a device called a fundoscope or photographed using retinal imaging technology that magnifies the optic nerve. If anything unusual is found, you may be sent for further examination.
Further tests may be needed when tonometry results indicate high intraocular pressure, if you have a family history or are at increased risk of glaucoma. An eye specialist can also perform a fundoscopy as part of a routine check-up.
Advanced imaging
Because glaucoma is a complex disease with many causes and symptoms, an eye specialist may perform a combination of comprehensive examinations. Other specialized tests you may have include a visual field test, fundus imaging, optical coherence tomography (OCT) or pachymetry, which measures the thickness of the cornea.
Treatment of glaucoma
The treatment of glaucoma is individual and not always as clear-cut as, for example, in the case of surgery cataract. In other words, there is no single ideal treatment for glaucoma.
Target pressure
After the examination, the eye specialist determines the next procedure according to your specific situation. Generally, however, it will calculate the ideal target pressure in the eye and try to lower or work on your pressure to reach the target value. This can be achieved with eye drops or medication, operatively or a combination of both.
Operative methods:
- Laser surgery– blocked parts of the trabecular meshwork are opened with a laser.
- Minimally Invasive Glaucoma Surgery– Surgery in which micro incisions are made to divert or open blocked ducts. These operations are quick, with minimal complications and quick recovery.
- Surgery with cutting– the cut opens the channel and reduces the pressure. These operations include trabeculectomy, sclerotomy, viscocanalostomy, and canaloplasty. Your optician or ophthalmologist will provide you with more information.
- Insertion of a tube– a tube is permanently placed in the eye, which drains the aqueous humor and reduces the pressure.
In general, the chances of recovery after green procedure surgery are good if all contributing factors are managed. However, damage to the optic nerve cannot be reversed.
Lifestyle changes
In addition to surgery, glaucoma can be treated holistically and specific lifestyle changes may be recommended. It is important to give the doctor a full medical history and to mention all your hobbies and habits. For example, if you practice yoga or play a wind instrument, this can affect your eye pressure.
As previously stated, diabetes, blood pressure (high and low), and chronic medication use must be captured. It is also recommended to stop smoking, eat healthy and exercise regularly.