Diagnosis

You can find out if you have long-sightedness by having an eye test at an opticians.

Find an opticians near you.

Having an eye test at least every 2 years is usually recommended, but you can have a test at any time if you have concerns about your vision.

For some people, including children under 16 and those over 60, eye tests are available free of charge on the NHS. Find out more about free NHS eye tests to check if you qualify.

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.

Page last reviewed: Tue Aug 2022 Next review due: Wed Feb 2020