An eye test explained

What happens during an eye test?

The first stage normally involves a pre-test, which can be carried out by the optical assistant or your optician. They'll begin by asking you a series of questions to know more about your lifestyle and the history of your eyes - if you've been having any problems with your eyes at all or if you've had issues with your general health recently.

Some of the questions they might ask you are:

• Do you take any medication?
• Do you already have a prescription? And if so, do you already wear glasses?
• Do you have any eye problems or genetic health history, such as glaucoma?
• Do you have any issues or concerns with your current vision?

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 left eye and the right eye.

Once this assessment is carried out, there are a few tests, with the following tools that your optician will use:

Your optician's assessment will involve looking for signs and symptoms of eye diseases or other medical conditions, including:

• 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: Astigmatism, hyperopia (long-sightedness) and myopia (short-sightedness) are some common refractive errors that can be detected during a test. These conditions are easily corrected with eyeglasses or contact lenses. In severe cases, surgery using the latest technology may be an option.
• Strabismus: Sometimes described as 'crossed' or 'turned' eyes, strabismus is detected by assessing whether the eyes are aligned correctly. Patients with this condition may be unable to judge the depth of the visual field correctly.
• Amblyopia: Often a result of strabismus (a condition in which the eyes don't properly align with each other when looking at an object), amblyopia (a lazy eye) 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 an optician will assess you for include glaucoma and diabetes.

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