Myopia or short-sightedness is a very common eye condition that affects the patient’s vision. The condition causes objects in the distance to be blurred while closer things can be seen clearly. Approximately 1 in 3 people in the UK are thought to have myopia and it can range from mild to severe which affects the treatment options necessary. Untreated myopia is one of the most common causes of vision loss.
This is a cross section of the eye which shows how the light travels through the various parts. The light goes in through the cornea, through the pupil and lens of the eye and the rays of light focus at the back of the eye.
With myopia the light does not focus on the light sensitive tissue (known as the retina) at the back of the eye, instead it focuses slightly in front of it. This causes blurred vision as the light is not focused correctly to produce a clear image which can be interpreted by the brain.
Myopia is usually caused by the eyes not developing properly which causes it to not transmit the light correctly into the retina. Generally the eye is formed slightly too long, creating a greater distance between the front of the eye and the light sensitive tissue known as the retina. This means the light focuses slightly in front of the retina rather than directly on it.
The condition can begin in early childhood; however it usually develops around puberty and gets more pronounced until the eye is fully grown.
It is not entirely clear why this happens although it is believed to be genetic and there is some correlation between environmental factors while the eye is growing and the development of short-sightedness. Myopia often runs in families and may be linked to focusing on objects close to the eye, such as books and computer screens, for long periods of time during childhood and puberty.
While it is unclear why exactly people develop myopia there are some factors that might increase the likelihood that you will.
Myopia is known to run in families so if one or both of your parents have the condition you are more likely to develop it yourself. Researchers so far have identified over 40 genes linked to short-sightedness which are responsible for the eye’s development, structure and signalling between the brain and eyes.
Research has found a link between the amount of time spent playing outdoors as a child, and the development or progression of myopia. It is thought that if a child spends a good amount of time playing and relaxing outdoors the risk of myopia is reduced, and the progression of existing short-sightedness is slowed down. This may be related to it being brighter outdoors and because children focus on a range of distances rather than only close objects.
Focusing on close objects such as books, computer screens and phones for long periods of time as a child may also increase your risk of myopia as this is the time the eye is developing. Generally a balance of close work with time spent outdoors is recommended to help encourage the eyes to develop properly.
Myopia is usually diagnosed through an eye test at your local opticians, which is recommended at least every 2 years. This is a quick and easy way to see if you have myopia and if so, what prescription lenses are needed to correct it.
You should consider going for an eye test, even if you have been tested within the past 2 years, if you experience any changes in your vision or difficulty focusing. Common symptoms include; headaches, eye pain, and eye strain. If you have myopia you might also find yourself holding books and other objects closer to your face to see them clearly, sitting closer to the TV or rubbing your eyes more often.
The most common treatment for myopia is prescription glasses or contact lenses although laser surgery is becoming increasingly used with a total of around 100,000 people with various eye conditions in the UK undergoing laser surgery each year.
Once you have had your eye test with an optician they should give you a copy of your prescription to take away which, unless otherwise specified and tested, will be for glasses only. This can then be used to order glasses online as it gives you your unique specifications to ensure the lenses are made exactly to your needs.
The thickness and weight of your lenses will vary based on the strength of your prescription which indicates whether you are mildly or severely myopic. This can be reduced by purchasing thinner lenses, otherwise known as high index lenses, which allows your lenses to fit more easily into the frame and reducing the weight on your nose.
Help with the cost of glasses may be available through NHS vouchers if you are eligible, for more information see the NHS website.
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If you would like to try contact lenses you will need to book a consultation for this with your optician separately, which also requires a valid eye test. Once you have had your consultation you should be provided with your prescription for contact lenses only, including a recommended lens type or brand, which can be used at any retailer including online.
Some people prefer contact lenses as they are more lightweight and are almost invisible, while others find them more difficult to use than glasses. Contact lenses can be a great option but require more care and attention to lens hygiene.
Occasionally opticians use a technique called orthokeratology which is when the patient wears hard contact lenses overnight which slightly changes the shape of the cornea. This flattens the cornea and may help patients to focus more easily. This treatment is not a cure for myopia because the cornea usually returns to its original shape, but it can help reduce your dependency on contact lenses and glasses.
A newer method of treating conditions like myopia is laser surgery which is when lasers are used to burn away small parts of the cornea and reshape its curvature. This means the light is focused better on the retina at the back of the eye. There are 3 main types of laser surgery:
These procedures are carried out under local anaesthetic in around 30 minutes, and often you can be back to normal the following day.
The results are usually good and 9 out of 10 people report a significant improvement in their vision, although it may not be possible to completely cure your myopia. It is also important to note that laser surgery may not be able to correct your vision as well as corrective lenses.
Contact lenses are very low risk, but it is important to maintain a high level of lens and personal hygiene, disinfect reusable lenses thoroughly and avoid sleeping with them in due to the risk of infection. Contact lenses also increase your risk of eye infection as it is easier for your eye to come into contact with bacteria, it is important to be aware of this and to have regular check-ups with your optician.
Laser surgery does have some risks and side effects, including a small risk of more serious complications which affect 1 in 500 patients. More common side effects include; dry eyes, reduced night vision or a haze around bright lights. Most of these are easily treatable and pass within a few months after the procedure. There is a risk of removing too much of the cornea which affects 1 in 20 people which can result in long-sightedness.
If you are short sighted your SPH values will appear as minus values, for example Right SPH -1.00.
Myopia bilateral simply means both of your eyes are myopic or short sighted, this would show on your prescription as a minus figure in both SPH values for example:
Right SPH -1.00
Left SPH -1.25
Long-sightedness (hyperopia or hypermetropia) means the patient struggles to focus on objects up close, but can see more clearly on objects further away. Short-sightedness is the opposite in that the patient can focus on close up objects but will struggle to see into the distance.