As we grow our eyes grow too. The clear, light-focussing parts of the front of our eyes can change less than the rest of the eyeball. That means the place where they focus the images of the world can become mis-matched to where the retina is, leading to the retina receiving an unfocused, blurry image. Near-sightedness, or myopia, occurs when the eyeball grows too long. In that case only things that are near are clearly focused. Eye glasses, contact lenses, or corneal surgery can correct the focus but overly long eyes can lead to sight-threatening disease. Basically, the retina becomes stretched too thin and can crack or detach, sometimes producing blindness. The risk of glaucoma is also higher. At-risk persons are said to have high-myopia.
In many urban areas in Asia over 50% of younger people are high-myopes. Myopia was relatively rare in those communities until the 1960s when it began to rise sharply. This means that as they age these communities are facing a looming epidemic of serious eye disease. The prevalence of myopia is growing rapidly in Australia. Vision ACTion scientists and their Partners have been instrumental in discovering that the single-largest cause of high-myopia is insufficient time spent outdoors in sunlight, especially for younger children. Our eyes are so good at “getting the exposure right” (see above) that we don’t realise that indoor lighting is thousands of times dimmer than outside. We evolved to live outside. The lack of bright light tells our eyes to grow more. Once that exuberant growth has started it is harder to stop. This means our increasingly indoor lifestyle driven by schooling and insufficient outdoor play is condemning children to serious eye problems in their later years. Aside from behavioural modification Vision ACTion has ongoing clinical trials on preventative therapies to help slow myopia once it has started.