Vision is a dominant sense and is essential in every aspect and stage of daily life.
It is taken for granted all the time.
However, when there is limited or no vision, all facets of life are affected including reading, learning, movement, schooling and working.
The eyes play a critical role in vision and any eye condition can affect vision.
Everyone who lives long enough will experience at least one eye condition that will require care.
Vision impairment can have serious consequences for the individual throughout life, many of which can be alleviated by quality eye care.
While common eye conditions like refractive errors or cataracts are often the focus of eye care, other more insidious eye conditions like glaucoma are often overlooked.
Glaucoma is a condition in which there is increased pressure in the eye due to fluid building up in the front of the eye.
If not diagnosed or treated early, it leads to vision loss due to damage of the optic nerve which connects the eye to the brain.
It affects all ages but is most common in senior citizens and Asians.
Other risk factors of glaucoma include family history in first degree relatives (parents and/or siblings), obstructive sleep apnoea, diabetes mellitus and myopia.
Malaysian data
Data on the prevalence of eye diseases in the Malaysian population is limited.
A study from Universiti Malaya Medical Centre, published in 2008, reported that cataract (385, 32.9%), was the most common eye disease seen followed by glaucoma (274, 23.4%).
The 2014 National Eye Survey found that the prevalence of blindness was 1.2% of the population, the main causes of which were cataract (58.6%), diabetes (10.4%) and glaucoma (6.6%).
A 2020 publication reported that the prevalence of glaucoma in Malaysia is increasing.
This is not surprising as the number of senior citizens have been increasing.
Types of glaucoma
The most common is primary open angle glaucoma which develops over many years and is due to gradual blockage of the drainage channels in the eyes.
Acute angle closure glaucoma is uncommon and is due to sudden blockage of eye drainage causing rapid increase in eye pressure.
Secondary glaucoma is due to an eye condition like inflammation (uveitis).
Childhood (congenital) glaucoma is rare and occurs in very young children due to an eye abnormality.
Features
There are usually no symptoms initially.
Glaucoma develops slowly (over years) and affects the edges of vision (peripheral vision) initially which is the reason why many people are unaware of the condition.
It is often detected during routine eye test.
The symptoms, if present, include blurred vision or rainbow-coloured circles around bright light.
Sometimes, it can develop suddenly with features that include intense eye pain, tenderness around the eyes, seeing rings around lights, blurred vision, red eye, nausea, vomiting, and/or headache.
Both eyes are usually affected although it may be worse in one eye.
Diagnosis
There are a number of tests used to diagnose glaucoma.
The pressure in the eyes can be measured by an instrument called a tonometer.
A small amount of local anaesthetic and dye are applied to the front of the eye.
Then a light is shined into the eye and its pressure measured by the tonometer which is placed gently on the eye surface.
An alternative is the measurement of the pressure by a different instrument that uses a puff of air without touching the eye.
Gonioscopy is an examination of the fluid filled space between the coloured part of the eye (iris) and the front of the eye (cornea), from which fluid usually drains out of the eye.
The examination helps in determining whether this area, called the “angle” is open or closed (blocked), which affects how fluid drains out of the eye.
Gonioscopy is usually performed in a dark room.
A visual field (perimetry) tests for missing areas of vision.
If the light spots shown are not seen at the edges of vision, it may mean that glaucoma has damaged vision.
The optic nerve is assessed for any damage from glaucoma.
This is done by dilating the pupils followed by examination with a slit lamp (microscope with a bright light); and/or optical coherence tomography (a non-invasive test that uses light waves to take retinal images).
The medicines used to dilate the pupils may affect driving temporarily.
As such, it is important to make alternative transport arrangements after this examination.
Treatment
It is not possible to restore any loss of vision prior to the diagnosis of glaucoma; however, treatment can help stop the worsening of the vision loss.
The treatment depends on the type of glaucoma.
Eyedrops are the main treatment.
There are different types but they all reduce the pressure in the eyes.
They have to be used as directed.
Its side effects include eye irritation.
Some may not be suitable for certain medical conditions, in which case, alternatives will be considered.
Laser treatment is recommended if eyedrops do not improve symptoms.
It is used to open up the blockage and/or reduce the production of fluid in the eyes.
Laser treatment is carried out after local anaesthetic drops are applied to numb the eyes.
Eye drops may still be needed after laser treatment.
Surgery is recommended in the uncommon situation when eye drops and laser treatment have not been effective.
The objective of the different surgical procedures is to improve drainage of the fluid in the eyes.
Following treatment, regular follow-up will be necessary for monitoring and checking of the response to treatment.
Limited knowledge
Local studies of the awareness and knowledge of glaucoma are limited.
A 2004 study done in academic staff of the University Malaya revealed that 71.5% were aware of glaucoma.
However, this was a highly selected population segment.
Another study of 329 Shah Alam, Selangor, residents, published in 2020, revealed that only 25.2% of the respondents were aware of glaucoma and it is associated with ethnicity, religion, education,and household income.
Only 11.9% had chronic illness, of which about 70% had high blood pressure.
Prevention
Preventive measures to protect the eyes will reduce the risk of vision loss from glaucoma.
Although there is no evidence for population-based screening for glaucoma, its early detection and treatment are critical to avoid blindness.
This is particularly so when there is limited awareness and knowledge of glaucoma in Malaysia.
It is prudent for anyone with risk factors for glaucoma to have a comprehensive dilated eye examination to detect glaucoma early and start treatment.
Even if one does not have risk factors, it is advisable to have a comprehensive dilated eye examination by 40 years of age.
The maintenance of a healthy weight, physical activity, avoidance of smoking and controlling blood pressure are healthy behaviours that will prevent diabetes and other non-communicable diseases associated with glaucoma.
After its diagnosis and commencement of treatment, it is vital to adhere to medical instructions to prevent worsening of glaucoma.
Last but not least, increasing awareness and knowledge of glaucoma would help its early detection and treatment, thereby preventing blindness, for readers and their family members.
Dr Milton Lum is a past president of the Federation of Private Medical Practitioners Associations and the Malaysian Medical Association. For more information, email starhealth@thestar.com.my. The views expressed do not represent that of organisations that the writer is associated with. The information provided is for educational and communication purposes only, and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.
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