What happens during an eye test?



During a test, your eyes will be examined both internally and externally, although how they are tested can vary depending on where you go.

The top reasons to regularly visit your optician

  • Your eyes and prescription can regularly change as you get older
  • An eye test will ensure your contact lenses are as comfortable as possible
  • Opticians can catch some health conditions early, allowing them to be treated quicker
Learn more about keeping your eyes healthy


The optometrist will often begin by asking you some history about your eyes and general health - if you’ve been having any problems with your eyes at all or if you’ve had any issues with your health recently.

You’ll then be asked to read from an eye chart with a number of letters on it. This may be the classic type or a projected version. The optometrist will often cover one eye at a time, to root out any discrepancies between the two.

Once done, there are a few tests that are common to most opticians…

The Tonometer

The non-contact tonometer is used to test the pressure inside of each eye. It is practically always used on patients over the age of 40 but is carried out on all patients at many optometrists.. The tonometer sends a number of small puffs of air against each eye which slightly flattens the front part of the eye (the cornea). The length of time it takes to flatten the cornea is converted by the instrument into an accurate measurement of the pressure inside the eye.

While this might feel a little funny, it’s an important test. High pressure can be an indicator of the early stages of glaucoma, which could be sight-threatening.

The Autorefractor

An autorefrector is used to find out how well your eyes focus and can be very useful in determining an approximation of your prescriptions. You’ll simply be asked to focus on an image or point of light, the optometrist will then simply ensure your eye is in full view of the machine and take a quick measurement.

The Opthalmoscope

The Opthalmoscope is a handheld tool the optometrist will use to clearly see inside your eye. A light will be shone into your eye, allowing the optometrist to see into your pupil to the back of your eye known as the fundus. You may be asked to put in eye drops before this test in order to widen your pupils, but this is pretty uncommon.

The Slit lamp

This one is particularly important for contact lens wearers. A powerful illuminated microscope is used to examine the outer surface of your eyes, allowing the optometrist to check how well your contact lenses are fitting or for any abnormalities or scratches to your cornea (the clear front part of your eye.

Why should I get my eyes tested?

No matter how old you are or how healthy you feel, it is always important to receive regular eye examinations from a qualified eyecare professional. While an eye test is certainly a good way to find out if your vision could be improved, a thorough eye examination will also check the health of your eyes. In fact, opticians can spot certain illnesses not directly related to the eyes, or help detect serious problems such as diabetes or high blood pressure.

How often should I get my eyes tested?

This can vary from person to person but most optometrists recommended taking a thorough eye test every two years. However, it is recommended that patients over 70 are tested more frequently (probably every 12 months) to catch any health problems early.

It’s also recommended that younger children are tested annually, as children’s vision can change very rapidly at this stage of their lives.

What Problems May Be Detected in an Eye Examination?

When you attend an eye test, the specialist will carry out a series of examinations to decide whether you would benefit from glasses or contact lenses. He will also assess you for common diseases of the eye and for signs and symptoms of other medical conditions which may be evident through the results of the examination.

The conditions which the specialist will examine you for will include the following:

  • Difficulties focusing: Children may not be able to focus properly due to developmental issues while adults may experience a decline in their focus as a result of their advancing age.

  • Refractive errors: More commonly known as long or short-sightedness or astigmatism, refractive errors are easily corrected with glasses or contact lenses. In severe cases surgery may be a realistic option

  • Strabismus: Sometimes described as 'crossed' or 'turned' eyes, strabismus is detected by assessing whether the eyes are aligned correctly. Patients with the condition may be unable to judge depth of field correctly.

  • Amblyopia: Often a result of strabismus, amblyopia can cause permanent impairment in vision. In patients with this condition, the brain will effectively 'close down' the image from the affected or weaker eye. A common solution is to place a patch over the stronger or correctly-aligned eye for periods of time.

  • Eye teaming problems: Effective vision relies on the two eyes working jointly and in cases where this does not happen the patient may suffer headaches, difficulty reading or eye strain.

  • Diseases of the eye: Many common diseases of the eye are asymptomatic in the early stages but can be identified during a regular eye examination. Earlier detection increases the likelihood of treating the diseases and reducing the probability of irreversible loss of vision. Examples of the diseases a specialist will assess you for include glaucoma and diabetic retinopathy.

What Treatment Will I Receive?

After an examination, your optometrist will advise you on next steps. This can include a prescription for glasses or contact lenses for any vision problems that can be easily corrected. You may also be advised to try some vision therapy, sometimes known as vision training, which will help to build your eye coordination and control. Very ocassionally you might be asked to see your GP or an eye specialist if there is some further investigation or treatment required.

If no problems are found with your eyesight, then you may find the only requirement is to return in another couple of years for a regular check-up.