What is a refractive error?
Refractive error is the most common type of eye disorder and causes blurred vision. There are several different types of refractive error including long-sight, short-sight, astigmatism and anisometropia.
How do normal eyes see clearly?
The eye has two parts that focus light to form a clear image on the light sensitive area at the back of the eye called the retina.
- The cornea – the clear, curved front surface of the eye
- The lens – a clear, flexible structure inside the eye
What is long- sight (hypermetropia or hyperopia)?
In long-sight the eye is either shorter than normal from front to back, or the cornea or lens is not curved enough. The light focuses behind instead of on the retina. Vision is usually better for distance than near, but distance vision may also be affected.
Most young children are slightly long-sighted and often no treatment is needed. If too much long sight is present then your child may have to over focus in order to see clearly. In some cases this can cause one eye to turn inwards (a convergent squint). It may also cause headaches and eye strain.
What is short- sight (myopia)?
Short sight affects approximately 1 in 3 people in the UK. The eye is either longer than normal from front to back, or the cornea or lens are too curved. The light focuses in front of rather than on the retina. Vision is usually better for close up than distance, but near vision may also be affected.
Short- sight usually develops between 6 and 13 years of age. Children born prematurely are more likely to be short- sighted.
What is astigmatism?
In astigmatism the front surface of the eye (cornea) is more curved in one particular direction. The eye is often said to be shaped more like a rugby ball than a football. Straight lines may appear curved causing objects to appear out of focus or distorted for all distances. Astigmatism can be present with long -sight or short- sight. Astigmatism may be present at birth or may develop later as the eye grows.
What is anisometropia?
Anisometropia is when there is an unequal amount of long-sight, short-sight or astigmatism between the two eyes. One eye may see a more blurry image than the other and this can lead to a lazy eye (amblyopia). For more information please see the leaflets “What is amblyopia?” and “Treatment of amblyopia”.
How do you test for refractive error?
Your child will have a glasses test which is known as a refraction. This is carried out by an optometrist (optician).Your child will usually need to have eye drops put into each eye. These enlarge the pupils and relax the focusing muscles inside the eye. This helps to give the most accurate measurement of the size and shape of the eyes. The optometrist can then decide if your child needs to wear glasses.
How is refractive error treated?
All types of refractive error can be treated with glasses. If it is recommended that your child wears glasses then you will be issued with a prescription to take to a local optician.
Please see the leaflet “Children’s glasses” for more information. Contact lenses are not generally recommended for young children except in certain situations.
How long will the refractive error last?
This very much depends on how strong the prescription is. Every child is different. Some children will grow out of the need for glasses. Others will require glasses as an adult.
Your child will have regular measurements (refraction) and the optometrist will advise if any change is required.
Will glasses give clear vision instantly?
Not necessarily. Correcting short-sight (myopia) generally results in instant clear vision, however, children with other prescriptions might take some time to adjust to their glasses.
Will my child need to wear their glasses all the time?
Yes, while vision is developing, it is recommended that children should wear their glasses constantly through the day.
Will my child still need to wear their glasses when their vision has improved?
Yes, we recommend that glasses should continue to be worn, especially while their vision is developing, unless otherwise advised by their orthoptist, optometrist or ophthalmologist.
How often will my child need to have their glasses checked?
As your child’s eyes grow the glasses prescription is likely to change. Glasses tests are generally done annually, unless otherwise advised by their orthoptist, optometrist or ophthalmologist and you will be informed of any changes.
For further information
Contact details
Appointments Office
Please contact the appointments office to change or cancel an appointment: 0191 282 4444
Monday to Friday 9am to 5pm (excluding Bank Holidays)
Orthoptic Department
To speak to an orthoptist about treatment: 0191 282 4434
Monday to Friday 9am to 5pm (excluding Bank Holidays)
PALS (Patient Advice and Liaison Service)
For help, advice and information about NHS services. You can contact them on Free phone 0800 032 02 02, e-mail northoftynepals@nhct.nhs.uk or text to 07815500015.
If you would like to find accessibility information for our hospitals, please visit www.accessable.co.uk
Useful websites
If you would like further information about health conditions and treatment options, visit the NHS website.
