Myopia (short-sightedness) is often accepted as an inconvenience for which spectacles and contact lenses remedy the blurred vision.
The factors thought to play a role in the development of myopia include:
Genetics: Having both parents short sighted is thought to have more influence than long hours of reading and close work.
Environment: Time spent outdoors seems to be linked to less myopia in children. Encouraging children to take part in outdoor activities may therefore be another approach to consider.
Reading/writing/working very closeto objects.
As well as an inconvenience, myopia is also associated with a number of eye diseases such as retinal detachment, glaucoma and macula disease. A study in 2012 (1) presented a particularly persuasive argument for myopia control by demonstrating that the risk of developing glaucoma and cataract associated with myopia is comparable to the risk of stroke from smoking greater than 20 cigarettes per day. In the UK, myopia is approximately three times greater in 12 to 13-year-olds compared to six to seven-year-old children (2), this highlights the need for early intervention to slow down myopia progression.
There are a number of myopia control strategies purported to work, however many lack evidence-based research. A study in 2011 looked at the effects of some of the interventions to slow down myopia progression (3). This review looked at how effective various approaches were in children aged 6 to 18 years. The authors included 23 studies (4,696 children in total) in the review. The treatment most likely to be effective was eye drops (Atropine) but these either caused sensitivity or blurred near vision or were not yet available to buy. Under-correcting myopia appeared to increase rather than slow down myopia. Although children wearing bifocal and varifocal spectacles did not become as myopic as those wearing single vision lenses, the effect was very small (0.16D). A trial of three spectacle lenses designed specifically for myopia control found no significant treatment effect.
Of the contact lenses studied, gas permeable lenses and ordinary soft lenses showed no evidence of reducing myopia development. One study compared bifocal soft contact lenses with ordinary soft lenses and found that, after one year, myopia in the bifocal wearers had not increased as much. The difference was about half a dioptre (0.56D).
The review concludes that: "none of the interventions studied had slowed myopia progression in a clinically meaningful manner". The most effective treatment so far was medication, i.e. eye drops, but their use was limited and not practical. Other methods, such as corneal reshaping contact lenses (orthokeratology) and other bifocal soft contact lenses were considered 'promising'.
Orthokeratology has been shown in some studies to slow myopic progression by 50% on average in children (4-6). Future studies will need to find out whether any effects are sustained after the treatment is discontinued and also determine how the treatment helps to control myopia.