What is myopia?
Myopia, or short-sightedness, causes your vision in the distance to be blurry, but your vision up close remains clear. About half of the UK population is short-sighted, and myopia is becoming increasingly common throughout the world. Most people with myopia have healthy eyes, but are unable to focus on objects in the distance. This problem can usually be corrected with glasses or contact lenses.
Pathological myopia, however, is much more serious. It causes severe short-sightedness due to degeneration of cells at the back of your eye which cannot be corrected with glasses or contact lenses.
Once patients become short-sighted, myopia cannot be reversed, so prevention is viewed as the best approach.
Causes of myopia
Myopia is one of the most common causes of sight impairment worldwide, currently affecting 1.4 billion people. By 2050, it is predicted that five billion people (half the world’s population) will be short sighted.
Short-sightedness is caused by the lens in the eye being unable to focus on the distance. People with myopia have relatively long eyes, so light is focused in front of the retina instead of directly onto it. If a child is diagnosed with myopia, they will continue to get more short-sighted as the eye continues to grow throughout childhood.
Exact causes of myopia are currently unknown, but recent research funded by Sight Research UK and carried out by Dr Denize Atan and her team at the University of Bristol showed that, on average, as a population, we become more myopic for each additional year we spend in education.
Evidence from other studies suggests that this may be because we spend less time outdoors, reducing our exposure to natural daylight. Other risk factors include environment, diet, and genetics. Insulin signalling also appears to influence the normal growth of the eye.
Myopia is more prevalent in countries adopting a Western diet and lifestyle and many of the genes that increase the risk of myopia are involved in insulin/glucose signalling and obesity/fat metabolism. As the Western diet tends toward greater consumption of energy-dense foods, one hypothesis is that compensatory increases in blood glucose and insulin levels send increased growth signals to the eyes which causes the distortion typical of myopia.
Pathological myopia is a rare condition thought to be inherited. It is usually diagnosed in early childhood and is due to an abnormal elongation of the eyeball in the growing child. This can happen quickly, however, causing a rapid loss of vision.
Symptoms of myopia
The main symptom of myopia is blurry vision when looking at objects in the distance, while your vision up-close remains clear. Other signs include: squinting, eye strain, headaches, feeling fatigued when driving or playing sports.
People with pathological myopia have a much greater risk of developing several eye conditions that cause much more significant and permanent sight loss. For instance, the lifetime risks of myopia leading to glaucoma or cataract are comparable with the risks of stroke from smoking 20 cigarettes a day. Complications of pathological myopia also include increased risk of retinal detachment, abnormal blood vessel growth, leading to bleeding in the eye, and other degenerative changes.
If you notice any of the above symptoms, schedule an eye test with your optician who will be able to detect myopia with simple vision tests and recommend the most appropriate next steps. This could be the prescription of glasses or contact lenses, and in case of rapidly worsening symptoms, a referral to your local eye clinic.
Short-sightedness can be corrected with glasses or contact lenses. For more severe cases, refractive surgery (or laser eye surgery) can be performed. There is no cure for myopia; current treatments only slow progression. Prevention is widely seen as the best approach to reduce the number of people losing their vision as a result of short-sightedness.
Future treatments for myopia
Current research funded by Sight Research UK, Dr Denize Atan at the University of Bristol is investigating the association between insulin signalling and short-sightedness, with the potential for a new treatment option.
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