Myopia, also called nearsightedness or shortsightedness, is the eye condition where objects nearby or a short distance away are clear but objects that are far away are blurred. It is caused by the eye being slightly too long. Myopia typically begins in childhood.
In Australia, the rate of myopia is predicted to approach 50% by 2050.
Risk factors influencing myopia development include
- Age – the younger you start to develop myopia the higher your risk of developing high myopia
- Ethnicity- South East Asian heritage have a higher risk of progression than Europeans
- Family history- One myopic parent increases your risk of myopia development 2-3 times and two parents increases that risk by up to 6 times
- Time spent outdoors- Time outdoors is protective against the development of myopia and is not associated with outdoor activity itself. It is recommended that children spend 2 hours a day outdoors.
- Time spent on near work – A child spending a lot of time indoors (reading or on electronic tablets, etc.) and very little time outside is 2-3 times more likely to develop myopia
Myopia is associated with significant sight-threatening risks later in life such as cataract development, Glaucoma, retinal detachment and macular degeneration. Reducing myopia progression, myopia control, is therefore important to reduce these risks as well as the impact on quality of life and the associated effects on cost of living and health care.
The significant scientific advances in the past decade have given better insight into what causes myopia to progress. It is understood that peripheral hyperopia (long-sightedness) in myopic eyes is a driving force for myopic progression. The eye elongates as a result of the peripheral hyperopic defocus which in turn causes an increase in the degree of myopia.
Myopia control does not reverse the amount of myopia that is present. It aims at minimising the total amount of growth after initiating treatment so that we limit the incidence of high myopia.
There are various avenues for myopia control:
- Orthokeratology: these contact lenses aim to control the progression of myopia by correcting for peripheral hyperopic defocus (which is thought to be a major contributing factor to the progression of myopia).
- Myopia control designed contact lenses: these lenses also control myopic progression by correcting for peripheral hyperopic defocus. They are typically a daily disposable lens worn only during waking hours.
- Multifocal soft contact lenses: this avenue seeks to control myopic progression by correcting for peripheral hyperopic defocus. They are the same lenses that are worn by adults to help read clearly and are typically a daily or monthly-disposable lens worn only during waking
- Spectacle lenses: Myopia control spectacle lenses which work on the peripheral hyperopic defocus model and Bifocals can reduce myopia progression by up to 30% depending on the level of myopia present.
- Atropine eye drops: Atropine is an anti-muscarinic drug that typically causes pupil dilation and cycloplegia (loss of accommodation). Low doses, have been shown to be effective in controlling myopia with few side effects.
There are currently no published long-term studies that satisfactorily answer the question of how long myopia control treatment must be sustained. Clinical experience, however, suggests that children undertaking treatment must continue at least until the end of their teenage years. Alternatively, if the myopia has been shown to be stable for an extended period of time, then consideration can be given to discontinuing the treatment.