Now that we have accumulated a bit of a log of centimeter measurements, it is time for us to start working on preventing the damage caused by your child’s close-up focus activities.
As you know by now, the primary driver behind myopia is the strain caused by looking at objects up-close, for extended periods of time. You now already know to limit close-up time to an hour or less at a time, and to get good breaks that involve distance vision, rather than more close-up. For the life long vision health of your child, these habits are more important than any prescription discussion we will have here. The foundation to permanently reversing and preventing myopia, is to limit close-up strain.
You also already know to not allow your child to view items at less than 50-60cm distance (unless the child is myopic and we adjusted the distance, temporarily, to account for shortsightedness). As you enforce these habits – breaks and minimum distance – your child will develop a sensitivity to extended close-up work, and be seeking distance and breaks on his/her own, eventually. The important thing here is to build that foundation.
We will discuss close-up sensitivity, and it’s importance, in an upcoming installment in more detail.
Again, please be entirely clear about this. No amount of eye exercises or prescriptions can successfully stop myopia on their own. The foundation is maintaining distance, and breaks. Only with that foundation observed, does any of the future installment content serve to improve your child’s eyesight.
We will use up to two prescriptions, depending on your child’s myopia degree, to begin reversing it’s course. If your child is at -1D or lower, we only need one prescription. Your child should not be wearing any sort of minus prescription, ever.
If your child has higher myopia, we will use two prescriptions. One for close-up work, and one for regular distance viewing. The distance prescription will be adjusted to encourage active focus, vs. the passive (harmful) focus that a regular minus prescription would create.
For this and the next installment, we will focus on the close-up prescription. Later, we will discuss the distance prescription.
The close-up prescription is designed to change the focal plane that the child’s eye perceives. We will artificially create a new focal plane, that will allow active focus to happen up-close (not possible for most people, without a prescription). The active focus will help us reduce eye strain, and also reverse the onset caues of myopia.
In most child cases, this is a plus lens prescription. It is identical to what is normally prescribed to far-sighted individuals. This prescription will change where the light focuses in your child’s eye, creating a new focal plane, where your child will be able to see what we will refer to later on as the edge of blur.
No need to get ahead of ourselves, all of this will come together in the coming installments.
This process is entirely harmless. We want to make sure to listen to the child, if there is any discomfort, or headaches, as with any sort of work or habit.
All that the differential prescription will do, is slightly change focal plane. This is relevant to adults as well, even if you have excellent eyesight, you might want to use a plus lens for part of your close-up focus – to keep training your focusing muscle and maintain peak eyesight.
What is dangerous on the other hand, is the use of minus prescriptions as many optic shops like to prescribe. These move the focal plane in your child’s eye in the opposite direction, creating passive focus (no need for your child’s eye to make any effort at all to focus). Beyond that, since those glasses are made to enhance distance vision, at up-close range they simply increase eye strain.
Close-up focus + Full prescription minus lenses = Increasing Myopia
You will be able to verify the accuracy of all of this yourself, by using Snellen and centimeter measurements. The use of plus lenses (paired of course with maintaining minimum distance and breaks) will improve measurement results, while wearing minus lenses will cause worse results (often in as little as a matter of 30-60 days).
You want to know the high and low values of your child’s centimeter results.
Find out the following:
Look at the variance as well (difference between left and right eye distance results), and record it.
We want to do at least three days worth of these readings. A morning and an evening centimeter each day will do fine. If there is a big change at any given day, add a fourth day to create a more accurate average.
You will use these results to choose the correct near-focus prescription for your child. This may seem like a small challenge the first time you do it, but with a little practice it will become second nature. This is also something you will want to repeat every few months, to catch any eye strain early on, and make regular adjustments as appropriate.
Checking your eyes is much like any other simple self check you can do easily, for yourself. It is a life long, very simple tool, to catch bad vision habits before they cause any real impact on your eyesight. Teaching your child early (and always, always keeping it fun), will give him/her the best chance to protect natural eyesight for a lifetime.