SINGAPORE - It is Healthy Vision Month, a good time to go for an eye check-up if you have any complaints about your vision or any eye problems.
We are not talking about just getting your vision checked at the optical shop.
A comprehensive or complete eye exam - which can only be done by a specialist - involves a series of tests that will also check for eye diseases, such as glaucoma, diabetic eye disease and age-related macular degeneration, on top of other disorders.
"You can pick up many diseases, such as high blood pressure and diabetes, in an eye exam as these diseases cause changes in the eye," said Dr Gerard Nah, the medical director and senior consultant at W Eye Clinic.
Many eye diseases often have no warning signs and the only way to detect them early is through a complete eye exam. Yet, many people who are at risk of these diseases are not getting their eyes checked regularly, say experts.
"We have indirect data showing that in Singapore, among those with eye conditions, a large proportion remain unaware of their condition," said Dr Anna Tan, an associate consultant with the vitreo-retina service at the Singapore National Eye Centre.
Recent data from the Singapore Epidemiology of Eye Diseases showed that over half of the diabetic population were unaware they had diabetic retinopathy, despite having visual impairment, she said.
"This implies that as they were unaware of their disease and the effect of diabetes on their eyes, they were not actively attending the necessary yearly eye check-ups."
ARE EYE CHECK-UPS A MUST?
All diabetic patients are advised to go for an eye check-up at least once a year, said Dr Tan.
Those with a family history of glaucoma should also attend routine eye screening even if they have no symptoms, she said.
Elderly people above the age of 65 years are another group that should have eye exams as they are more prone to problems.
"If they notice problems with their vision or any other eye problems, they should seek medical advice and go for an eye check-up," said Dr Tan.
Those who reach 40 years of age may also want to get their eyes checked as that is when early signs of diseases can start to appear.
"In general, it is not necessary for a young, healthy patient with no eye complaints to go for routine eye check-ups," she said.
"When in doubt, consult your general practitioner for advice on whether a specialist eye check-up is required."
A specialist eye check-up or comprehensive eye examination is aimed at arriving at a diagnosis for someone who is seeking medical help for a problem with his eye or vision, said Dr Nah.
It is also done for patients undergoing vision correction such as Lasik, as the eye specialist will examine the eye to look for any previously unrecorded condition which may complicate the surgery, added Dr Nah.
It is different from a simple eye screening, which is sometimes offered by medical institutions for free.
That would generally involve only simple tests such as a vision assessment and an examination using a magnifying instrument called the slit lamp, which uses bright light to illuminate eye structures.
If the doctor suspects that you have an eye problem during the screening, he will then order further tests, said Dr Tan.
Eye check-ups are painless but discomfort can come from having bright light shone at one's eyes, said Dr Nah.
The cost of a comprehensive eye check-up starts from $75 at the Singapore National Eye Centre or from $100 at Dr Nah's W Eye Clinic.
What to expect at a comprehensive eye exam
The doctor could take 20 to 30 minutes to go through your complaints and medical history before he conducts an eye examination.
VISUAL ACUITY TEST
This measures how well you can see. You will be asked to identify different letters of the alphabet on a chart.
REFRACTION OF THE EYE
This assesses any degree of correction needed. The doctor may shine a light into your eye to measure the refractive error. You will be asked to look through a device that contains a combination of lenses to determine which gives you the sharpest vision.
INTRA-OCULAR PRESSURE (IOP)
This test measures the pressure of the eye to screen for glaucoma, a disease that damages the optic nerve. Elevated pressure is a possible sign of glaucoma.
There are two ways of doing this. In the first method, the eye is anaesthetised with eye drops. The doctor will then use an instrument to touch the eye gently to test for eye pressure.
However, some people and children do not like having eye drops and are unable to cooperate with any test that involves something touching the eye.
The other option is to use a machine which emits a puff of air on the eye to measure the reactive changes in the shape of the eye. The smaller the change, the bigger the pressure.
Some people may find this a bit of a shock, though it does not hurt.
SLIT LAMP EXAM
A slit lamp is a microscope that magnifies and illuminates the structures in the front or back of your eye. This helps doctors to spot and observe diseases like cataracts, glaucoma and age-related macular degeneration.
The doctor will usually dilate your pupils with eyedrops to keep them from shrinking when he shines light into the eye.
Dilated examinations can only be done under the supervision of medical practitioners as diagnostic eye drops are used to dilate the pupil. In rare cases, the dilating drops may induce a spike in eye pressure, which would require specialist attention.
The dilation typically lasts for four to six hours and causes side effects that include blurring, glare and loss of accommodation or the ability to read. Do not drive as your vision may be blurred.
AMSLER GRID TEST
This tests for early retinal disease involving the central vision, using a grid of evenly spaced horizontal and vertical lines.
You will be asked to report any holes, or wavy or distorted lines on the grid.
PUPIL REACTION TEST
Doctors do this to test the reflex that controls the size of the pupil in response to light and to a near target, for instance, to see whether the optic nerve is functioning well.
Other tests will be done if needed. For example, if a squint or misalignment of the eyes is noted, the doctor may then perform a test to measure eye movements and the patient's ability to see in 3-D.
Source: Dr Gerard Nah, medical director and senior consultant, W Eye Clinic
This article was first published on May 22, 2014. Get a copy of Mind Your Body, The Straits Times or go to straitstimes.com for more stories.