Inability to see close objects clearly, commonly known as longsightedness
- Most often detected at about the age of 5; may not cause problems until middle age
- Sometimes runs in families
- Gender and lifestyle are not significant factors
The transparent cornea and the lens act together to focus light rays and create a clear image on the light-sensitive retina at the back of the eye. Hypermetropia (longsightedness) occurs if the eyeball is short relative to the combined focusing power of the cornea and lens. When the image falls behind the retina, it causes blurred vision that is often worse when viewing near objects. Young people with hypermetropia often see distant objects very clearly because the lens is flexible and changes focus easily, but with age, focusing ability lessens and distant vision is also affected.
What are the symptoms?
Mild or moderate hypermetropia will probably not affect vision in young people because they can compensate by focusing the lens, but, the more severe the condition, the earlier in life symptoms may appear. Symptoms of severe hypermetropia, which may be apparent from infancy, can include:
Lack of interest in small objects.
Difficulty with reading or following picture stories.
If the eyes are not equally affected by hypermetropia, they may be unable to focus together on the same object. Without early treatment, young children may develop crossed eyes (see Strabismus) and may eventually lose vision in one eye (see Amblyopia). You should take your child to the doctor immediately if you notice any of the symptoms described here. If you have trouble seeing near objects clearly or have difficulty in reading or doing other close work, you should visit your opto-metrist for vision tests. These problems may indicate that you have presbyopia, which develops earlier in people with hypermetropia than in most people.
What might be done?
Your optometrist will check your visual acuity and the level of detail you can see, and then assess the severity of hypermetropia. Although the condition is sometimes detected in children during routine vision testing at school, all children who have a family history of severe hypermetropia should be tested before the age of 3 because early treatment is important.
Hypermetropia can be corrected with contact lenses or glasses that have convex lenses (see Glasses and contact lenses). The focusing power of the eye decreases gradually with age, and your prescription may need to be updated regularly. People who have hypermetropia may be helped by laser treatment that increases the focusing power of the cornea (see Surgery for refractive errors).
Hypermetropia does not cause complications, but people who have the condition are more prone to acute glaucoma, a condition that must be treated promptly. Regular tests for glaucoma (see Common screening tests) are therefore especially important.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.