Causes of Myopia
The causes of myopia are multi faceted. Instead of trying to identify a singular cause of myopia, its more appropriate to view them all as possible interactions. That is the reason why many research in myopia causes has often given conflicting results because its often not possible to hold any of these variables as constant on the clinical research subjects.Our eyes are constructed for far work. Traditionally a human is lifestyle is that of a hunter, or farmer, of someone who spend little time indoors. That is why our eyes in a relaxed state see far (See Accomodation System and Accomodation Process), which is the state that it should be in most of the time.
However, as human is lifestyle moves more and more into the city, we spend most of time in door, and doing near work. Many children from birth until school going age, hardly spend their time outdoors. As a result, their eyes are constantly in a tense state. A myopic eye is more suited for nearwork lifestyle as tense less than a non myopic eye when doing nearwork.
With this background, the eye starts to evolve to suit a lifestyle of nearwork, ie myopic.
Hence, its no surprise that children whose parents are both myopic will have a higher tendency to be myopic.
Genetics always plays a part in myopia development; it will make one more or less susceptible to myopia. Hence if both parents are myopic, there would be higher tendency for their children to be myopic.
We often would presume pre-school going children whom are already myopic is more highly susceptible to myopia progression, hence its control more difficult.
It has also being observed that children born pre-maturely before their 9 months term tends to be more susceptible to myopia. The earlier they are born before their full term, the higher their myopia susceptibility.
The likely reason is that their eyes left their natural protective environment and forced to function despite it not being fully developed.
Nutrition is important, especially during the babies growth stage.
The eyes needs nutrients to develop, and its only in recent years that its found that DHA is important for the healthy growth of the eye.
Human breast milk happens to be rich in DHA and other antibodies, which is why its known as the perfect food for babies. However, with our hectic city lifestyle, many mothers do not have the luxury of breastfeeding beyond their 2 to 3 months maternity leave. They have no choice but to rely on formulas milk. Formula milk typically do not have as much antibodies or nutrients as compared to human milk. And only the expensive range comes with DHA, AHA etc. The speculation is that this may be a reason why children nowadays are more susceptible to Myopia.
Staying in an environment of much space and land gives the eye much opportunity to see far and hence relax it the moment one step out of their house. Conversely, city dwellers tend to focus at the lift, their neighbours doors, the street, the cars; the eye is less required to focus on distant object. The constant tensing of the eye makes it highly susceptible to myopia. (See also Evolution and Myopia)
Our modern lifestyle is a major causes on our myopia. Our lifestyle constantly make us to read a book, watch TV, play computer games, play handheld games, writing and working on the computers. This is especially so, where its common to see people reading, using laptop at the park, or walking around engaging in handheld games in the shopping centres.
Nearwork subject our ciliary muscles in our eyes to be in constant state of tension and goes into spasm. When this happens, its known as accommodative myopia (See Accomodative Myopia). When nearwork tension is not relief, it is believed to cause real myopia, ie the enlargement of the eye ball.
Lifestyle causation is an important factor in the development of myopia, and its one major are where we can make a difference.
The harmless looking spectacles too are a suspect for the progression of myopia. Some optometrist has observed that children prescribed with spectacles usually see a rapid increase immediately after.
The possible reason proposed is that spectacles lock our ciliary muscles constantly in a tense state in order for the eye to focus clearly on both near and distant object, thus aggravating myopia progression.
Low Light Condition and Myopia
When visual work such as reading or writing is done under inadequate work, it is often noted that our eyes tires easier. This is because under low light condition, our eyes tends to need to accommodate more to focus. Another possible reasons is that, with inadequate light, the amount of light sensitive retina cells that are activated to send electric pulse to the visual neuro is much less, resulting in the brains having to work harder to read the poor inadequate signals being sent in.
