Long-sightedness (hyperopia): symptoms, children, eye tests and correction

To see clearly, light has to be focused by the cornea and lens onto the retina at the back of the eye. Look After Your Eyes, the College of Optometrists patient site, explains that in long-sightedness the eyeball is slightly too short, so the point of focus is behind the retina. Moorfields compares it to a cinema projector set too close to the screen: the picture is blurred because the distance does not suit the strength of the lens.

Both sources note that the problem is mainly with near vision. Moorfields says hypermetropia can affect vision at all distances but especially close up. The NHS puts it more simply: you find it hard to see things nearby but see things far away clearly.

It is a different problem from the age-related stiffening of the lens that causes presbyopia. The NHS lists a stiffer lens due to ageing as one reason the eyes cannot focus properly, alongside the shape of the eye and of the cornea, so the two can overlap, particularly after 40.

The NHS lists the usual signs, and Look After Your Eyes adds a few. Eyes can compensate for a while, which is why symptoms often show up after concentrated close work or later in life when the focusing reserve fades.

• Words or pictures in books and on screens look fuzzy (NHS).

• Things are clearer when you hold them further from your eyes (NHS).

• Tired eyes after reading or computer work (NHS), and headaches (NHS).

• A need to screw up your eyes to see clearly (Look After Your Eyes).

• Moorfields adds that people with moderate to severe hypermetropia, or older people, may have difficulty seeing, tired eyes and trouble reading.

Young eyes behave differently. Moorfields says that many very young children have mild hypermetropia that gets better by itself as they grow older, and that in mild cases the natural lenses are flexible and often change focus to compensate. Children may not complain that they cannot see, because they compensate and have no comparison.

The warning sign is a turning eye. Look After Your Eyes says a long-sighted child may have one eye turning inwards towards the nose as they try to focus, which is a squint and may be more noticeable when the child is tired or unwell, and that they may develop a lazy eye, so an optometrist should see them without delay. The NHS agrees that young children with severe long-sightedness are more likely to develop other eye problems, including lazy eye and squint.

Because children under 16 (or under 19 in full-time education) are among the people the NHS lists for free eye tests, there is no cost barrier to checking a child you are unsure about.

The NHS says long-sightedness happens when the eyes cannot focus properly, because of the shape of the eye, the shape of the cornea, or a lens that has become stiffer, usually through ageing. It adds that it is often passed on from parents and cannot be prevented. Moorfields agrees that in most people there is no known cause, though it may run in the family, and notes that the proportion of people with hypermetropia increases with age.

Rarely, other conditions are responsible. The NHS mentions diabetes and eye cancer, while Moorfields mentions problems in the retina and microphthalmia, where an eye did not develop fully before birth. These are uncommon, but a thorough eye examination is one reason it is worth having a proper test rather than buying ready-made reading glasses and carrying on.

The NHS explains that an optometrist usually tests for long-sightedness by asking you to look at lights or read letters while different lenses are placed in front of your eyes, which shows how well your vision is working. The optometrist will usually shine a light into your eyes to check the back of the eye is healthy and may give eyedrops to get a better look.

Glasses or contact lenses are the usual treatment. Look After Your Eyes says long-sightedness can be corrected by either, and the NHS explains that they help your eyes focus so nearby objects are clear. The optician advises on the best option. The NHS notes contact lenses are usually only suitable for adults and may not suit everyone, and that people on some benefits, and children under 16 or under 19 in full-time education, may be entitled to an NHS optical voucher towards the cost; otherwise you pay.

Some people can consider laser eye surgery or lens replacement. The NHS says both are done awake under local anaesthetic; laser reshapes the cornea with high-energy beams of light, and lens surgery replaces the lens inside the eye with a plastic implant. It says these treatments are not usually available on the NHS, and to ask your optician whether they might be options. Whether a procedure is advisable depends on a full assessment of your eyes.

If long-sightedness is left uncorrected, the NHS says it may cause other vision problems, which for young children means a higher chance of lazy eye and squint.