What happens during an eye test
Your eyes will usually be tested by an optometrist (someone who's been specially trained to examine the eyes).
An eye test usually involves several different examinations including:
- measurements of the pressure inside your eyes
- checks to measure how well your eyes work together
- a visual acuity tests – where you're asked to read from a chart that has rows of letters that get smaller on each line
- a retinoscopy – where a bright light is shone into your eye to see how your eye reacts to it
If the tests find a problem with your near vision, you may be asked to repeat the visual acuity tests while different strength lenses are placed in front of your eyes.
This will help the optometrist find the right glasses prescription for you.
Understanding your glasses prescription
If an eye test finds that you're long-sighted, you'll be given a prescription for lenses to improve your vision. This can be used for glasses or contact lenses.
Your prescription will usually consist of 3 main numbers for each eye. These are:
- Sph (sphere) – a positive number here indicates that you're long-sighted, while a negative number indicates that you're short-sighted
- Cyl (cylinder) – this number indicates whether you have astigmatism (where the front of your eye is not perfectly curved)
- Axis – this describes the angle of any astigmatism you have
If you're long-sighted, the Sph number is the most relevant. This is given in a measurement called dioptres (D), which describes how severely long-sighted you are.
A score up to 3D is usually considered to be mild long-sightedness, while a score of more than 6D is considered to be fairly severe long-sightedness.