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Hypermetropia occurs when light is focused behind the retina. In reality, light cannot actually be focused behind the retina. So, the lens changes its thickness (becomes fatter or more rounded) which aims to bring the light into focus on the retina - a process called accommodation.

But, people with long sight cannot accommodate fully and so the light does not focus sharply and vision is blurred. This occurs because either the eyeball is too short, the cornea is too flat, or the lens cannot become round enough.

People with a minor degree of long sight can usually see at distance, and their near sight is clear. However, a person with long sight may get tiring of the eyes, often with a headache and vision discomfort. People with more severe hypermetropia are not able to see near objects clearly in focus. Long sight means exactly what the term suggests. You are sighted (you can see) distant (long) objects.

The causes of hypermetropia are usually genetic (hereditary). Long-sightedness can occur at any age but it tends to become more noticeable above the age of 40 years.

In rare cases, hypermetropia is caused by other conditions such as diabetes, small eye syndrome (microphthalmia), cancers around the eye and problems with the blood vessels in the retina.

Many babies and very young children tend to be slightly hypermetropic but usually grow out of this by about 3 years of age.

A particular type of age-related long-sightedness called presbyopia occurs because the lens of the eye becomes more stiff with age.

The main symptom is a difficulty with near vision. 'Tiring' of the eyes (asthenopia) is common and long-sighted people may have headaches and uncomfortable vision.

There may be difficulties with seeing with both eyes (binocular vision), as the brain will tend to ignore signals coming from the most long-sighted eye. Lazy eye (amblyopia) or squint (strabismus) can also occur in hypermetropia. Long-sighted people may have difficulty with depth perception (3-dimensional vision).

Glasses

The simplest, cheapest and safest way to correct long-sightedness is with glasses. Convex prescription lenses (called plus lenses) are used to bend light rays slightly inwards. The light rays then have a lesser angle to bend back to focus when travelling through the cornea and lens. As a result, the light rays focus further forward - on the retina. There is an enormous choice of spectacle frames available, to suit all budgets. Glasses are seen as more acceptable these days, and younger people may even regard them as a fashion accessory.

Contact lenses

These do the same job as glasses. Many different types of contact lenses are available. Lenses may be soft or rigid gas-permeable. Contact lenses can be daily disposable, extended wear, monthly disposable, or non-disposable. Your optometrist can advise which type is most suitable for your eyes and your long-sight prescription. Contact lenses often work out more expensive than glasses and they require more care, and meticulous hygiene. They are suitable for older teenagers and adults, rather than for children.