Everyone living in the UK should have an eye test around once every 18 to 24 months, but if you wear glasses, suffer diabetes, are over the age of 70, or under the age of 16, you will need to go more regularly.
An eye test usually takes around 30 minutes and along with testing your sight the optometrist will check if your eyes are healthy and look for sign of eye disease. Here we give you a brief rundown on what to expect during an eye test.
At the start of the eye examination you will be asked a series of questions, such as: Do you wear glasses? Do you wear contact lenses? Can you tell me about your general medical history? Do you take any medication? Are you having any problems with your eyes or vision? Are there any eye or vision problems in your family's medical history? Once you have answered these questions, the painless but important eye test can begin.
Your eyes will be examined both externally and internally, and this will enable the optometrist to make a clear assessment of the health of your eyes and identify any other underlying medical problems.
The first test is usually the retinoscopy, which takes place in a darkened room where you will be asked to stare at a target. The optometrist will then shine a light into your eyes to see the way your eyes reflect light when different lenses are passed in front of them. Next up is the refraction test, which fine-tunes the prescription, estimated by the retinoscopy. An instrument called a phoropter is put in front of your eyes and you will be asked which of each choice of two lenses looks the clearer. Based on your answers, the optometrist will be able to determine how long-sighted, short sighted, astigmatic or presbyopic you are.
Once these tests are complete you will have the visual acuity test, which is most well-known eye test. This test involves looking at an eye chart, usually of varying sized letters and you must read them aloud. After this older patients may be shown an Amsler grid, which is a pattern of lines in a square check formation, with a spot in the middle. You will be asked to stare at the dot and will then tell the optometrist if you notice any variations in the regularity of the lines. The Amsler grid tests your central vision and can be used to detect the onset of age-related vision problems.
Other tests you may undergo in a comprehensive eye examination include the field of vision test, which measures your peripheral vision and involves flashing lights in your periphery of your vision while you stare at a light, and the cover test, where your eyes will be alternately covered while you focus on a distant object. By looking at how much each eye has to move to focus on the object, the optometrist can detect problems that could lead to the condition commonly known as a ‘lazy eye’.
For the optometrist to get a closer look at the internal structures of your eyes you will take the slit lamp test, which involves looking into your eyes through a powerful microscope. The eyelids, cornea, iris, conjunctiva, retina, optic nerve and macula are among the things that can be seen through this microscope, and the optometrist can check for signs of cataracts, macular degeneration, diabetic eye disease and corneal ulcers.
Finally, the optometrist will check your colour vision. For this eye test you will be asked to look at numbers formed of dots against a background of dots of a different colour. Patients with normal colour vision will see the number as it is meant to be, while those with colour blindness may see a different number or even no number at all.
The tests mentioned above are the most common tests performed in an eye test, but there are others that the optometrist may want to do if he or she is concerned about any aspect of your eyes or vision. After the eye test you will be advised when you should go back for another test and will be told whether you need further treatment.