关于幼童弱视，您可能不知道的几件事

One of the nursery books and videos I remember sharing with my first-born was by the American author and illustrator Richard Scarry, and the theme song lyric that goes “you can be anything you want to be…” That was before the introduction of the iPhones and iPads.

So much of a child’s growth is dependent on good vision in the past two decades with the proliferation of the use of digital devices. One of the most important gifts you can give your child is…not an iPad, but to ensure that his or her eyes develop fully and not become a lazy eye, which in scientific parlance, is called amblyopia. This will definitely help in allowing them freedom in pursuing their dreams and ambitions in live.

To start with, children undergo maturation of their visual system and the process is pretty much complete by the time they turn eight. Should there be any disturbance of this process of maturation such as from eye conditions like squint (misalignment where the eyes seem to be looking at different directions), refractive errors like high long-sightedness or astigmatism, childhood cataract or droopy eyelid, the equal process of maturation between the eyes can be derailed due to the phenomenon of inter-eye rivalry, where the better eye takes it all and the poorer eye fails to mature fully. Yes, even in the “world” of eye development, Darwinism seems to be at work where survival goes to the fittest.

The truth is most of us are born with two eyes that are meant to see things from a slightly different angle. This slightly different perspective between the two eyes serves the purpose of giving us binocular, stereoscopic vision i.e. 3-D vision through which we perceive depth and distance. A single eye can find clues regarding depth and distance from size and shadows, but this may not be sufficient for some activities that require good depth judgement, for example, intricate horological work or performing life-saving surgery. Stereoacuity or 3-D vision is assessed by eye tests such as Titmus or Worth 4 dots tests which are done at specialist eye clinics.

They can be categorised into gross or fine stereoacuity. Gross stereoacuity is usually sufficient for most activities of daily living while fine stereoacuity is often advisable for tasks involving more demanding hand-eye coordination.

For higher grade steroacuity to develop, both eyes need to be matured fully and be able to see sharply. The time window for this is usually limited to the first eight years of our lives with the earlier years being more crucial than the latter years. For kids who unfortunately suffer from eye conditions like squint or astigmatism, especially when the severity of these conditions is not symmetrical in the two eyes, it is imperative that not only are their primary eye conditions get managed and treated but the development of their more seriously affected eye needs to also be safeguarded by penalizing the better eye. Which is why you may have sometimes seen kids patching their eyes, and the commonest scenario would be kids patching their straight eyes as a treatment to prevent lazy eye from happening in the drifting eye that is prone to becoming a lazy eye.

Apart from a drifting squint eye which is most commonly an outward- drift followed by -drift, and astigmatism, other worrying eye conditions that may result in lazy eye include refractive errors like high degrees of long-sightedness which often compound an inward drifting eye. These relatively common reasons are why in Singapore, health services have in place school-based eye checks from as early as 2 years of age to identify at risk children and recommend further management should significant reduction of eyesight be found.

Other less common childhood eye conditions that may cause a lazy eye include eye diseases affecting premature children such as retinopathy of prematurity, childhood cataract, droopy eyelids and actually, anything that may occlude and obscure the eye’s line of sight, including overly long bangs covering the eyes over long duration of time, which is one very valid reason to keep young kids’ hair well away from their faces.

Should there be mild amblyopia, computer-based vision training (such as a program called Vivid vision) may have a role. Speak to us to find out more.