If you are short-sighted (myopic), you will normally have difficulty seeing things at distance, for example distinguishing number plates and road signs whilst driving, or reading subtitles on the TV. Usually, things up close are relatively clear, such as computers, reading and using your mobile phone. Other signs of short-sightedness include squinting the eyes when looking in the distance in order to try to achieve a clearer image (by limiting the amount of light entering the eyes, the blur reduces slightly), but this causes symptoms such as headaches and can cause the eye and frontal head area to feel strained.
Feeling tired and weary when carrying out concentrated distance vision tasks (e.g. driving, cinema, watching TV) can also be a symptom of short-sightedness that is not being corrected.
Short sightedness (myopia) occurs when the eyeball is too long. This causes light rays entering through the front of the eye to focus in front of the retina, rather than on it. It can also be due an abnormally shaped cornea or lens compared to the length of the eyeball.
Short sightedness typically starts in early childhood years during the developmental and growth period, and you may be at slightly higher risk if either or one of your parents is myopic. In most cases, it stops deteriorating and becomes stable by around the early ’20s but can occasionally continue to deteriorate with age. It is said that approximately 1 in 3 people are short-sighted.
Refractive errors are measured using the unit of dioptres, the higher the number, the more severe the error. People who are myopic are generally at higher risk of retinal detachment. The retina is inside the eye, at the back, and it sends signals to the brain in order to process the images that we see. Because the eyeball is too long in myopia, it can cause a thinning and weakening of the retina, which in turn can cause it to detach and pull away from the structure underneath, the choroid. This is a severe and sight threatening condition and needs to addressed immediately by an ophthalmologist at the eye hospital. It often presents with a sudden onset of flashing lights and floaters.
Patients who are highly myopic can also be at higher risk of cataract and glaucoma. Cataract is the clouding of the crystalline lens inside the eye, which is normally caused by the natural ageing process. Glaucoma is an eye disease which is caused by elevated intraocular pressure (pressure inside the eye) which in turn causes damage to the optic nerve in the eye, leading to loss of peripheral vision.
A much rarer condition, called pathological myopia (or malignant myopia) is where the eyeball continues to grow excessively and rapidly with age and this can, in turn, cause the retina and surrounding tissue to become damaged with the sheer speed of growth. It can start from a fairly young age (early childhood) and gets progressively worse as the patient becomes older. Unfortunately, there’s no treatment to stop the growth of the eyeball, but it is important to have regular checks with an ophthalmologist in order to treat any associated complications of the condition.
By far the most common and affordable way to correct short sightedness is by getting glasses or contact lenses. The lenses are concave and they can bend the light entering the eye, and focus it onto the retina. Unfortunately, contact lenses can cause dry eyes or infections, especially if hygiene compliance is not followed, but most people agree that they are far more convenient when playing sports or being outdoors and exposed to the elements.
Depending on the severity of your short-sightedness, you may need to wear glasses or contact lenses full time or only for distance vision tasks, such as driving or at the cinema/watching TV.
There’s also a treatment called orthokeratology, which is where patients wear special rigid gas permeable (hard) contact lenses at night which reshape the cornea whilst they sleep. When the lenses are removed in the morning, the cornea temporarily retains its shape so that the patient can see clearly during the day.
This does fade gradually as the day progresses, and the contact lenses need to be worn the following night. This is not a permanent solution for myopia but is an option for those who are not suitable for refractive surgery.
Refractive surgery is an option after the prescription has stabilised, usually by early ’20s.
Implantable Contact Lenses (EVO Visian ICLs) known as phakic IOLs are another surgical option for correcting short-sightedness. This treatment option is ideal for those whose prescription is too high for laser surgery, or whose corneas are too thin. EVO Visian ICLs are surgically placed inside the eye (behind the iris) to help focus light onto the retina. There is no chance of rejection by the body.
Clear Lens Replacement
Clear Lens Replacement is a refractive surgery option for people who are presbyopic (need reading glasses, usually after the age of 45 years), where the crystalline lens of the eye is replaced with an artificial (intraocular) lens that refocuses the light, to allow it to focus onto the retina. Normally trifocal lenses are implanted which allows the patient to experience clear vision at distance and near.