For most of us, either in childhood or adulthood, there comes a time during our eye check-up appointment that the optometrist tells us that we have acquired either myopia or hyperopia. In other terms, we may know them as near or far sightedness. But what exactly do these terms mean, and how can understanding them help us to make informed decisions regarding our eyes? Let us delve into the science behind these two common terms!

What is myopia?

We will begin with myopia which refers to being near sighted. I’m not sure about everyone else, but my brain always has a hard time wrapping its head around the fact that near sightedness does not actually mean you struggle to see things near. In fact, being near sighted is when you have no problem seeing things up close, but struggle to see at distances. The way I remember, is the condition means the opposite of what its name suggests. Now with that technicality out the way with, let us explore what near sightedness means for our eyes.

When we have myopia the shape of our eye prevents the light from bending properly, and instead of the light aiming directly onto your retina which allows you to see, it lands in front of your retina which causes our far away vision to become blurry. Changes in eye shape may include the front part of your cornea being sharply curved, or the shape of your eye being longer or oval shaped instead of round. Myopia is commonly first detected in children aged between 8-12 years, and generally can worsen during teenage years as the eye continues to grow. This is not to say that you cannot be diagnosed with myopia at a later age, however, it is more common to be diagnosed during childhood.

What is hyperopia?

With the above in mind, it comes as no surprise that hyperopia is the term for far sightedness, which you guessed it, means the lack of vision to things near. This causes objects that are close to appear blurry- like when reading a book, the words may not be as clear. Yet, objects that are far away can be seen visibly with no trouble. Hyperopia happens when your eye does not refract (bend) the light properly due to either your eye being shorter, or your cornea being too flat. Instead of the light bending onto your retina, the light focuses behind it, affecting your ability to see nearby objects clearly.

Most children experience mild far sightedness due to their eyes not yet being fully grown. In majority of cases, they do not experience blurry vision, and as they grow older, hyperopia can be reduced or corrected completely. This is because as children grow, their eye becomes longer, enabling light to bend onto their retina instead of behind, yet for some, this condition transcends into adulthood. As we grow older, normally from the age of 40, our near vision can start to deteriorate. This decrease in vision is caused by our eye’s lens hardening and being unable to change shape. This condition is called presbyopia and differs from hyperopia due to its underlying cause, yet both conditions are refractive errors that cause the same symptoms.

Symptoms of myopia and hyperopia

Aside from the difference in the range of sight, common symptoms of myopia and hyperopia both include:

- Headaches

- Eyestrain

- Squinting of the eyes to either see at close or far distances

How to diagnose

If you or your child is experiencing the above symptoms, an eye check is recommended to be able to determine the condition of your eyes. To test for myopia or hyperopia, this is normally done through a comprehensive eye test that will require you to read the letters on an eye chart. The optometrist will most likely use a phoropter which is an instrument that measures for any refractive errors of your eyes. For young children, a retinoscope may also be used to determine refractive errors by measuring the position of light in regards to the eye. Before you decide that you need contacts or glasses, be sure to get a proper diagnosis from your eye doctor who will determine your condition and prescribe you with the correct power.

Correction of myopia and hyperopia

Depending on the severity of your near or far sightedness determines the type of prescription and treatment you may need. For myopia you will need spherical power of (-). Numbers that range from -0.25 to -3.00 dioptres indicate mild near sightedness, -3.00 to -6.00 dioptres show moderate, and -6.00 dioptres and above tell us that your myopia is high. Whereas the spherical power for hyperopia will be (+). An error of +0.25 to +2.00 dioptres is considered as low far sightedness, +2.00 to +5.50 dioptres indicate moderate far sightedness, and +5.50 dioptres and above show high hyperopia. Understanding your spherical power helps in understanding the severity of your eyesight, and if choosing to buy eyewear online, this helps to make the process a lot easier. Bare in mind to always get your eyes checked by a qualified optometrist before making any purchases of eyewear, as incorrect power can cause further eyestrain, and enable myopia to progress faster in children.

Glasses and contact lenses both aid in correcting myopia and hyperopia by refocusing light onto the retina. Ensure you take regular eye tests to keep track of your eyesight as it is prone to change as we get older, and new prescriptions may be needed. Bare in mind, glasses and contact lenses do not cure refractive errors such as myopia and hyperopia, but they do help to manage the problem. However, in children it is proven that multifocal lenses and ortho-k lenses can in fact significantly slow down and prevent myopia from worsening.

For more permanent methods, refractive surgery might be an option for you. This option usually is not recommended for children under the age of 18. Initially there is an outlay of cost, yet surgery provides long lasting results for a minimum of 10 years before natural changes of your eye or age can re-alter your vision. There are two main options for refractive surgery, the two including- refractive laser surgery and refractive lens exchange. Refractive laser surgery works by using a laser to reshape the cornea and to adjust how light travels through it. Whereas refractive lens exchange is where your eye lens is taken out and replaced with an artificial lens made specifically to correct either near or far sightedness. If surgery is an option you may like to consider, book an appointment with your eye doctor to discuss the intricate details of these procedures.

Are there ways to prevent myopia and hyperopia?

There are multiple factors at work that can predetermine the cause of refractive errors like myopia and hyperopia, such as genetic, environmental, and lifestyle factors. Whilst there is no way to prevent hyperopia, there are other ways (other than eyewear) to help prevent myopia in children.

- Encourage children to play outside: The rays of the sun provide natural light which puts less strain on the eye. There are studies showing that ocular UV exposure from being outdoors is more prevalent in people without myopia, showing a strong correlation between children who play outdoors to have a higher chance of avoiding myopia than children who don’t.

- Eye drops that slow down the rate of myopia in children: Specifically formulated eyedrops for near sightedness are to be placed in the eye once a day, normally before bedtime to prevent the eye from lengthening too much.

Remember, if myopia is left untreated it can lead to severe myopia which puts you at risk for a detached retina. This is where the tissue lining the back of your eye pulls away from the eye wall, and can potentially lead to blindness. Severe myopia can also make you susceptible to cataracts, or to contracting eye diseases such as glaucoma and myopic macular degeneration. If you suspect your myopia is worsening, do not wait and get your eyes seen to by your healthcare professional.