|Dioptric value (D)||(degree)||Focal|
Prescribed eyeglasses for myopia are dispensed with concave lenses by optician. Concave lens is also called negative lens (indeed bringing negative effect), minus lens or divergent lens. The lens drags the image of the distant object nearer for the eye to see as shown by F point in the diagram. That means concave lens is purposed for seeing distant object only. Concave lenses are not meant for reading book! All wearers may not take off the glasses when shifting from far object to near object because it is troublesome to do so every time. When concave lenses are used to see near object for the first time, the image is blurred. The eyes re-focus to see the near object. Prolonged re-focus makes the adjustment fixed, causing the eyes to be unable to see far objects anymore. The eyes have thus been wrongly trained to see near object only! Prescribed eyewear is like a walking stick or a drug. The more it is used, the more the user relies on it and finally the eyes degenerate. When seeing near object continuously, eyes are stressed, leading also to mental stress. Relaxed eyes and mind can initiate good vision.
Myopia rate shoots up quickly until myopia becomes an epidemic when eyeglasses prescription is introduced to a population. The more eyeglasses shops are opened, the more people become highly myopic. When a person first puts on concave lenses, the body tries to protect the person by making the person dizzy. Some optometrists request their clients to wear the glasses all the time, claiming that if this is not done, the myopia will become worse. But wearing myopia glasses all the time is the very way to accelerate the worsening of myopia. The unsuspecting person just follows what the optometrist says. When the person returns months later for a stronger prescription, the optometrist blames the worsening to genetics etc. Even worse, the optometrist prescribed two lenses with different power, causing left eyesight and right eyesight to be constantly imbalanced. Also the younger the person starts to wear concave lenses, the faster the myopia worsens. Some optometrists prescribe over-corrected concave lenses (higher power) for children, causing the children's eyesight to become worse faster. The victimized children do not know what is going on.
The very cause of myopia is seeing near object. It is absurd to let the eyes see close objects even closer by wearing concave lenses. Myopia at the early stage can be cured by itself by just eliminating the very cause of myopia. It is the natural ability of the body on self-healing for survival. The clear but artificial image given by lenses sends wrong signal to the body that no healing is needed. If a child cannot see the blackboard in class, then move the child nearer temporarily to the blackboard instead of giving a pair of concave lenses. Stop television or video game. Go out to play ball. Hold book further when reading.
The eyes are adaptive organs. High myopia happens because the eyes adapt to the glasses. The adaptability of the eyes is actually good. While the adaptation can be used to worsen myopia, it can also be used to help reduce myopia. Always read at a distance in which the letter is a bit blurred so that the eye will adjust to see the letter clearly. Myopic people develop a bad habit of seeing near distance only. Always see far away, for example when waiting at a traffic light. When reading from a book, a computer or a handphone, frequently shift the eyesight to somewhere far away. Thus do not face a wall when reading. Another bad habit is to stare. Develop good habit to always move the eyeballs when seeing two different points, instead of turning the head.
If a person has mild myopia (less than -3 D), avoid lenses if possible. People in poverty cannot afford glasses, so even if they may have had myopia before, it heals by itself. Thus the myopia rate is very low among population living in poverty, contrary to affluent society.
If a person's myopia is no longer mild (-3 D and over), get under-corrected (lower dioptre) lenses instead of lenses with full correction. The power can be rounded down to the nearest integer for dioptre (or hundred for degree) so that it is easier to remember. For example -4 D, -3.75 D, -3.5 or -3.25 can be rounded down to -3 D, even to -2 D if desired. This gives the eyesight opportunity for improvement. Do not wear glasses when reading from a book or a handheld device. Avoid wearing glasses all the time. Wear only when needed. The body has self-healing property. If the eyesight is blurred without glasses, the eyes will make effort to adjust to clearer vision. If the eyesight is always clear with glasses, the eyes will get lazy and stop improving. When a myope puts on glasses after a period of not wearing the glasses, the person will notice the vision is clearer than the time right before the glasses is taken off. On the other hand, when the person takes off glasses after a period of wearing the glasses, the person will notice the vision is fuzzier than the time right before the glasses is put on. Even so-called full correction is only valid for the time the eyes are tested. Just like blood pressure, human eyesight fluctuates throughout the day. Thus the lenses can become overcorrected later. Full correction can only be achieved by averaging the result of a series of eye tests performed a few times a day over a few non-consecutive days. However in certain countries, the shops will not sell under-corrected lenses.
If a person has perfect vision, the person should wear plus lenses (reading glasses) for prolonged near work such as reading to prevent myopia. The plus lenses push the image of the near object further away for the eyes to see. However reading glasses must not be worn when seeing far object otherwise hyperopia (farsightedness) can happen.Do not start wearing concave lenses even they are given for free.