Most cases of short-sightedness (myopia) are diagnosed by an optician during an eye test.

Opticians are healthcare professionals who specialise in diagnosing common eye conditions, such as short-sightedness. They also prescribe corrective lenses.

Eye test

During an eye test, your optician will test your vision with and without your glasses or contact lenses (if you wear them).

They will usually assess your distance vision, your near vision (for close work, such as reading) and your intermediate vision (for using a computer).

The optician will use a simple visual acuity test to assess how good your vision is. You may be asked to read from a chart that has a number of rows of letters that get smaller on each line.

If you have problems reading the letters at a distance that most people can read easily, it's likely that you'll be diagnosed with short-sightedness.

Your optician may refer your child to the hospital eye service. This may be because young children are more difficult to test, or because the optician would like an ophthalmologist or an orthoptist to carry out an assessment.

Ophthalmologists are doctors who specialise in diagnosing and treating eye conditions. Orthoptists are experts in checking children's vision and the balance of the eye muscles.

Retinoscopy

To measure how severe your short-sightedness is, your optician will use a test called retinoscopy, where a bright light is shone in your eye to see how your retina reacts.

You may also be asked to look at a chart through a series of different strength lenses to see how they affect your vision. This will help the optician to determine the strength your prescription should be.

Free eye tests

For some people, eye tests are available free of charge on the NHS. You qualify for a free NHS-funded eye test if you are:

• aged under 16, or aged under 19 and in full-time education
• aged 60 or over
• registered blind or partially sighted
• diagnosed with diabetes or glaucoma
• aged 40 or over and you are the parent, brother, sister, son or daughter of a person diagnosed with glaucoma, or you have been advised by an ophthalmologist that you are at risk of glaucoma
• eligible for an NHS complex lens voucher

You are also entitled to a free NHS sight test if:

• you receive Income Support or income-based Jobseeker's Allowance (not contribution-based)
• you receive Pension Credit Guarantee Credit
• you receive income-based Employment and Support Allowance
• you are awarded Universal Credit
• you are entitled to, or named on, a valid NHS tax credit exemption certificate
• you are named on a valid NHS certificate for full help with health costs (HC2)

People named on an NHS certificate for partial help with health costs (HC3) may also get help. You can also read about the NHS Low Income Scheme (LIS).