Myopia

What is myopia?

Myopia means short-sightedness. People with myopia cannot see things clearly in the distance without wearing glasses or contact lenses, but can see things clearly at close range.

Myopia is usually caused by the eyeball growing a little longer than it should.

Over the past 50 years, the proportion of people with myopia in the general population has doubled. Now around 25% of young adults in the UK have myopia. The longer the eyeball, the stronger the glasses required to correct distance vision. 

If a person's glasses are stronger -5.00 diopters, this is called 'high myopia'. The higher the degree of myopia, the higher the risk of developing serious eye complications later in life, which can permanently reduce vision. 

 

Symptoms of myopia:

Myopia can develop in childhood or adulthood, although it tends to stabilise from the age of 18 years. In addition, it may be associated with other eye conditions, such as astigmatism.

People with myopia find that things in the distance look blurred. Children who develop myopia often need to sit at the front of class to see the whiteboard. People may also develop headaches and eye strain.

What are the causes of myopia?

Myopia develops when the eye ball is too long in comparison to the focusing power of the cornea and lens. This means that light rays are focused at a point in front of the retina rather than directly on its surface.

Rarely, the cornea, the lens, or both are too curved causing the light rays to be out of focus.

Can myopia be prevented?

At present it is not possible to prevent myopia. Increasing the time children spend outdoors to at least 1.5 hours per day can delay the onset of myopia.

What is the treatment of myopia?

There are two aims to treatment: to slow down the worsening of myopia in children and young people, and to correct the optical problem of not seeing clearly in the distance.

At all ages, glasses can be used to correct blurred vision. Teenagers and adults may decide to wear contact lenses some of the time, and glasses at other times. Adults can also opt to undergo refractive surgery such as PRK and LASIK.

New treatments can slow down the worsening of myopia in children and teenagers. The following are currently available in the UK on private prescription:

  • low-concentration atropine eyedrops, prescribed by some ophthalmologists
  • special contact lenses such as orthokeratology or dual-focus lenses, prescribed and dispensed by some optometrists
  • special glasses with multiple optical zones, prescribed and dispensed by some optometrists

All of these forms of myopia management in children and young people require careful monitoring, ideally including six-monthly measurements of the length of the eyeball to ensure that the treatment is working.