Blurred vision can be caused by a number of different things, from conditions that simply need correcting with glasses or contact lenses, to medical emergencies like acute glaucoma. Underlying conditions, such as type 2 diabetes, can also cause blurred vision.
The commonest cause of blurred vision in children and young people, as well as adults, is myopia (short-sightedness). Symptoms often start around the onset of puberty and become more pronounced until the eye has developed fully. Early signs include sitting too close to the TV or holding reading matter too close to the face. The problem often comes to light at school when children are expected to focus on distant objects, such as a smartboard. Myopia is easily corrected with glasses or contact lenses. Later on, in adulthood, laser eye surgery can be very successful.
Hyperopia (long-sightedness) does affect a small number of children, and some children are born long-sighted, but the problem tends to correct itself as they grow. It’s important to have your child’s eyes checked regularly though, as uncorrected long-sightedness can lead to problems such as cross eyes or a lazy eye. Long-sightedness is commonest in adults from about the age of 40, when it is known as presbyopia. If you are long-sighted, you find it hard to focus on close-up objects, while your long-distance vision is good. Glasses, contact lenses or laser eye surgery can all help to correct the problem.
Age-related macular degeneration (AMD)
A common cause of blurry vision in older people is age-related macular degeneration (AMD). The macular is a small area in the middle of the retina that is responsible for central vision. In AMD, the macular degenerates and central vision is gradually impaired. AMD doesn’t cause total blindness, as peripheral vision remains unaffected.
As described in the name, age is one of the most important risk factors. Around one in 500 people aged 55-64 have AMD, which is a painless but progressive condition. This number rises dramatically to one in eight people aged 85 or over. Usually both eyes are affected, although one may deteriorate more rapidly than the other.
There are two types of AMD: wet and dry. Dry is the commonest, affecting 90% of sufferers. It occurs when the cells of the macula become damaged due to lack of nutrients and a build-up of waste products. Loss of vision is gradual, occurring over a number of years.
Around 10% of sufferers will develop wet AMD. This is less common, but more serious. It develops when abnormal blood vessels form underneath the macula and damage its cells. Without treatment, eyesight deterioration is rapid and central vision can be affected within a matter of days, so it’s very important to seek help if you notice any problems with your central vision.