This article will discuss what myopia is and how it can affect your vision. It will also look at what the common symptoms are, what treatments are available and how it can be controlled. Throughout the guide you’ll also find answers to some of the most frequently asked questions about this condition.
What is Myopia?
Myopia (also known as short-sightedness or nearsightedness) is an increasingly common eye condition with a third of all people in the UK suffering from it. When you develop myopia, you’ll be able to see close-up objects clearly whilst those in the distance will be blurry. The severity of short-sightedness can vary with mild cases requiring no treatment and more acute cases having a severe impact on vision.
Myopia tends to develop during puberty getting gradually worse until the eye has fully developed but very young children can also develop the condition. The signs that a child could be suffering from short-sightedness is frequent rubbing of the eyes, complaints of tired eyes or headaches, sitting too close to the TV or finding it difficult to read the whiteboard in school.
What Causes Myopia?
Myopia is usually caused when the eyes have grown slightly too long, meaning they’re unable to create clear images of distant objects. The exact causes of this remain unclear but many believe it is as a result of a combination of factors (both environmental and genetic), causing a disruption to how the eye should develop normally.
Understanding How the Eye Works
Light passes through the transparent layer located at the front of your eye (the cornea) before passing through the structure that sits behind the cornea (the lens). The light is then focused onto a layer of tissue at the back of the eye (the retina), which is light-sensitive and helps to create the images that are then sent to the brain (via the optic nerve).
In order for these images to be produced clearly, it’s important that your eyes are the right length and your corneas are evenly curved.
However, when you suffer from myopia, your eye(s) will usually have grown a little bit too long. Therefore, when you look at objects in the distance, the light isn’t being directly focused onto those light-sensitive cells in the retina but is instead focused slightly in front of it. This is what creates the blurry image, which is sent to your brain.
What Increases Your Risk of Developing Myopia?
As mentioned previously, there aren’t any direct scientific facts as to why people develop myopia but there are some things that increase the risk of you developing short-sightedness.
Myopia is something that tends to run in families so if one or both of your parents have developed short-sightedness, you’re more likely to develop it too.
So far, researchers have found over 40 genes that are linked to myopia and these are responsible for how the eye develops and is structured as well as how the signals are passed from the eyes to the brain.
Not Spending Enough Time Outdoors
If, as a child, you spend plenty of time outdoors, researchers have found that you decrease your chances of developing myopia and any existing signs of short-sightedness may develop less quickly.
It is thought that this may be related to the fact that light is much brighter outdoors. And relaxing and playing sports outdoors are also thought to be beneficial in reducing your risk of developing myopia.
Working On Close-Up Objects
Having a job that involves focusing on close-up objects all of the time (e.g. writing, reading or working on computers) can increase your risk of suffering from myopia. Working on handheld devices such as tablets and mobile phones can also increase this risk.
That’s why many specialists recommend an “everything in moderation” approach. So, whilst you should be encouraging your children to read, they should also be enjoying outdoor activities alongside playing computer games or watching TV.
What are the Symptoms of Myopia?
When you develop myopia you’ll probably start to notice that you can’t see distant objects as clearly as you used to. This may mean that you’re struggling to read road signs or have to sit closer to the TV to see it clearly. Your close-up tasks such as working on the computer or reading won’t be affected, though, and you will still be able to see nearby objects clearly.
Other signs that you may have developed short-sightedness include squinting, headaches and eye strain. Equally, if you start to feel tired when you’re playing sports or driving, this may also be a sign of myopia that hasn’t been corrected.
However, if you are experiencing these symptoms whilst wearing your contact lenses or glasses, you should contact your optician straight away as you may require a stronger prescription.
How is Myopia Diagnosed?
If you think you have developed myopia or you think your existing condition is getting worse, you should arrange to have an eye test as soon as you can. It’s advised that you have a routine checkup with your optician every two years, even if your eyesight appears to be fine, but you should book a test before this if you’re starting to feel concerned about your own or your child’s vision.
Some people are entitled to free eye tests on the NHS (including children under the age of 16 and children under the age of 19 who are in full-time education).
What’s Involved in an Eye Test?
An optometrist (someone who has been specially trained to perform eye examinations) will usually test your eyes. However, sometimes, children’s eyes are more difficult to examine, so they may need referring for an eye test at your local eye hospital service. And to make sure accurate measurements are achieved, they may need some eye drops which will help to dilate the pupil.
During your eye test, a number of different tests will be performed, these can include:
- A retinoscopy – where your eye’s reaction is tested by shining a bright light into your eyes.
- A visual acuity test – where you’ll have to look at a chart in the distance, reading the sequence of letters from it. These will get gradually smaller the further down you go.
- Checks that look at how well your eyes are working together.
- Tests that measure the pressure inside your eyes.
If, during these tests, the optometrist notices that there is a problem with your vision in the distance, the visual acuity tests may be repeated. During these repeated tests, lenses that have different strengths will be placed in front of your eyes and this will help to determine the prescription you require from your glasses.
What Does Your Glasses Prescription Mean?
When myopia is detected during your eye test, you may be given a glasses prescription that will help to improve your distant vision. Glasses or contact lenses can then be made to suit your prescription level.
Typically, your prescription will include three numbers for each of your eyes. The sph (sphere) which number will indicate whether you’re short- or long-sighted. If you’re short-sighted, a negative number will be shown whilst long-sightedness is indicated by a positive number.
The cyl (cylinder) number demonstrates whether you have astigmatism. If your eye isn’t perfectly curved at the front, this is classed as astigmatism.
Finally, the axis number will then explain what angle, if any, of astigmatism you have.
For myopia, it is the sph number that is the most significant and this measurement will be provided in dioptres (D), describing how severe your myopia is. Mild myopia is normally indicated with a score of -0.5D to -3D whilst anything over -6D is generally classed as “high” or severe myopia.
How Can Myopia Be Treated?
Myopia is most commonly treated with contact lenses or glasses but an increasingly common treatment is laser eye surgery. There’s also a newer technique of implanting artificial lenses, which is normally used when laser eye surgery isn’t possible (i.e. the myopia is severe) or it hasn’t worked.
Using the prescription your optometrist has provided you with, glasses can be made that are designed specifically to meet your eyes’ measurements (as sometimes, each eye may be different, requiring a different prescription in each lens). By wearing lenses that have been tailored to your prescription, this will make sure the light is correctly focused on your retina, preventing distant objects from looking blurry. Depending on how short-sighted you are will depend on how thick the lenses are.
As you get older, your eyesight is likely to change, meaning that you may require two pairs of glasses – one for your distant vision (e.g. watching the TV or driving) and one for close-up activities (e.g. reading or writing). In some cases, people prefer to have bifocal lenses, which provide you with one pair of glasses that can be used to look far away and close up without having to change your glasses.
Multifocal lenses (varifocal glasses) are also available which allow you to see close-up, middle and long distance objects through one set of lenses.
These work in much the same way as glasses, correcting your vision by focusing the light properly on your retina. However, many people choose to wear contact lenses because they’re almost invisible and are lightweight whilst others find them more inconvenient than glasses.
There are a variety of contact lenses available, including daily disposables which can be worn on a daily basis before being discarded, or they can be reused after they’ve been disinfected. Some contact lenses can also be worn for a longer period of time but many specialists advise that they shouldn’t be worn overnight as this can increase your risk of developing an eye infection.
Very occasionally, another technique may be used by some opticians, which is called orthokeratology. This helps to flatten the curve in your cornea by wearing hard contact lenses during the night, thus helping you to see more clearly during the day without using glasses or contact lenses. This isn’t a long-term cure for myopia because the cornea will normally return to its original shape, however, in some people, it does help to reduce the reliance they have on lenses.
When you visit your optician, they will advise which contact lenses are most suitable for you. And if you do decide to wear them, it’s crucial that you prevent yourself from getting any eye infections by maintaining good lens hygiene.
Laser Eye Surgery
To correct the curvature of your cornea, laser eye surgery uses a laser to cut away small sections of it, helping light to focus properly on your retina. Here are the three main types:
Photorefractive Keratectomy (PRK)
A small “flap” is created in the surface of the cornea before a laser is used to change the cornea’s shape by removing some of the tissue.
Laser Epithelial Keratomileusis (LASEK)
This is similar to PRK but instead of making an incision to create a flap in the cornea’s surface, alcohol is used to loosen the surface. A laser is then used to change the shape of the cornea before the flap is replaced in the cornea.
Laser In Situ Keratectomy (LASIK)
This procedure is very similar to LASEK but a smaller flap is created in the cornea’s surface by using a laser or microkeratome blade.
In most cases, these treatments will be performed on an outpatient basis, which means you won’t have to stay overnight in hospital. The entire treatment takes approximately 30 minutes to complete and the eye is numbed using a local anaesthetic.
Can You Prevent Myopia from Getting Worse?
Unfortunately, as children grow, myopia tends to get worse. The younger they are when they develop short-sightedness, the quicker their vision will deteriorate and the more severe it will be in adulthood (in most cases). At around 20 years of age, myopia tends to stop getting worse.
At present, there are no treatments that prevent myopia from progressing but it can sometimes be slowed by treating the eye with eye drops (atropine) or special contact lenses that are worn overnight. Research has demonstrated that atropine can help to slow down how fast myopia progresses but it also comes with some side effects when administered at a high strength; these include sensitivity to bright light and difficulty reading. In the UK, there are no low strength doses available commercially.
Bifocal and orthokeratology contact lenses can sometimes slow down the progression of myopia in children but in most cases, they won’t be as effective as the eye drops.