How eye tests work
If you want to protect your eyesight, regular eye checks are a must.
Our eyes allow us to read a book, enjoy the beauty of a sunset and see the people we love “so it’s important to have them checked regularly so that any issues can be detected and treated as early as possible”, says Margaret Knapman, Managing Optometrist at HCF Eyecare Associated Optometrists.
Making your appointment
When you ring to book in for an eye exam, make sure you mention family history (of glaucoma, for example) or health conditions (such as diabetes) that may indicate you need a longer appointment.
The optometrist asks questions to clarify the main reasons for your visit (if you’re experiencing headaches or blurred vision, or simply want an eye check-up).
Your eye check
In the consulting room your optometrist will conduct some or all of the following eye checks:
Visual acuity test
With one eye covered, you read letters of the alphabet from a chart, with the type getting smaller with each row. This measures your sharpness of vision.
Slit lamp check
A special microscope with a strong light illuminates the structures of your eye to allow assessment of your eyelids, lashes, irises, corneas and eye lenses.
Eye function tests
The optometrist tests your muscle function, eye coordination and peripheral vision by getting you to visually track a moving object, look at a distant target and by bringing objects or computer images into your line of vision.
Glaucoma causes a build-up of pressure in your eyes that damages the optic nerve. Tests for the condition include an optic nerve examination. During an optic nerve examination the optometrist may use pupil-dilating drops (which take about 20 to 30 minutes to work) and a small instrument called an ophthalmoscope to examine the optic nerve.
“As your vision may be affected for an hour or two after the test, you will need to catch public transport or have someone else drive you home,” Knapman says.
For the tonometry (or ‘puff of air’) test a small puff of air is directed into each eye. “The faster the return speed of the air, the higher the pressure, which may indicate risk of glaucoma,” she explains.
If you need or use glasses your optometrist will ask you to look through a series of different lenses and pick which one looks clearer to determine the most appropriate lens power. The prescription is handed to an optical dispenser who helps you choose your glasses frames and arranges for them to be made up with the prescribed lenses. This may take a few days or weeks.
While you look through an eyepiece that resembles a pair of binoculars a digital photograph is taken of one eye, then the other. “This high-resolution image is uploaded onto a screen,” says Knapman.“It allows your optometrist to view the back of your eye, including your retina, optic nerve and blood vessels, to check for signs of eye issues such as macular degeneration, cataracts, glaucoma and impacts of high blood pressure.”
EYE HEALTH ALERTS
Eyes can give doctors valuable insights into a range of potentially dangerous health conditions.
HEALTH CHECKS BY AGE: THE TESTS YOU SHOULD BE HAVING
Your guide to staying on top of your health, through every stage of life.
HOW TO GET THE MOST FROM YOUR GP VISIT
Maximising your time with your doctor can bring real health benefits.
SERIOUS CONDITIONS THAT CAN BE MISSED
Many serious conditions have vague or hidden symptoms. Here’s how to identify and screen for them.