When you visit your optometrist for an eye test, they will use a combination of specialist equipment and testing procedures to check the health of your eyes. The structure of your eyes will be assessed, and your visual ability will be measured, so understanding what procedures your optometrist employs to evaluate your eyes can help you understand the results of your test. Here's an overview of the four main components of a standard eye test:
Visual Field Testing
Visual field testing assesses your peripheral vision and involves looking straight ahead into a machine called a Humphrey Field Analyser. You place your chin on the edge of the machine, and stare into a dark inner compartment. As you look ahead, dots will appear in your peripheral vision, and you'll be asked to let your optometrist know each time you see a dot. This can allow the optometrist to establish if there's anything blocking part of your peripheral vision, which would need further investigation.
Colour-blind testing assesses your ability to see a variety of colour combinations, and it can also be used to determine if your ability to see colours has diminished since your last eye test. Your optometrist will turn the lights off in the examination room, and bright circles made up of coloured dots will be projected onto one of the walls. Within each circle there is a number, and this number should stand out to you and be easily identifiable if you have no problems with your colour vision.
Refraction testing is used to establish if you are long-sighted or short-sighted and will determine what strength of prescription glasses you require. The results of this part of your eye test can also help your optometrist diagnose a number of eye conditions, such as macular degeneration and retinal vessel occlusion, both of which can affect your central vision. You simply need to look into a phoropter machine, which automatically places a number of different lenses over each of your eyes. The machine measures how light bends as it enters your eye and whether it reaches the retina at the back of your eye at the optimum angle for clear vision.
Eye Pressure Testing
A number of eye conditions, such as diabetic retinopathy and glaucoma, can cause pressure to build up within your eyes, which can damage nerve endings and lead to vision loss. Intraocular pressure is checked using a tonometry machine, which delivers gentle puffs of air directly into each eye and records the resistance of your cornea to the pressure from the puffs of air.
A standard eye test assesses the health of your entire eye, and the results can help diagnose a number of serious health problems. For example, your optometrist can detect cell damage affecting your central vision even if you haven't noticed any changes to your vision, and this can be a sign of type 2 diabetes. So, if you're overdue an eye test, schedule an appointment with your optometrist as soon as possible.