How it works Contents For the sceptics Bibliography Resources Order the book Forum Contact us Home page


Does the method change depending on age? When is the right time to change the additional lenses?

FAQ n. 39 - Power Vision System - I’ve identified three people who seem to be interested and motivated to carry out the Power Vision visual rehabilitation program. All three cases have the following training schedule:Ocular stretching three days per week, three times per day, wearing positive +2.50 lenses on each eye in all activities that allow it (reading, working at computer).

a. Marco (my son): –6.25 right eye (RE) –5.50 left eye (LE) (asymmetry due to keratoconus). After having trained for four weeks, now he usually wears –5.50 RE and –4.75 LE and according to Snellen tables he has full sight now, even though after working(viewing within 10 feet distance) he notices some worsening. He is the only one who doesn’t do any exercise regarding fogging/retinal defocus.

b. Francesca: –1.25 RE and –0.75 LE.
Next Sunday she’ll finish her first week of training. Her schedule includes also the exercises of defocus/focusing.

c. Massimo –2.00 per each eye. Same story as Francesca’s.

My questions:

a. Does the method change depending on age?

b. Should I correct the training schedules of my three samples?

c. When is the right time to change the additional lenses? Should they stay the same? Should both myopes and hyperopes always wear the additional lenses in near viewing (a kind of everlasting visual hygiene)?

d. Marco has told me that he feels better (and sees better) wearing his present glasses. When is the right time to change graduation for distant viewing?

- Answers David De Angelis

Entire ocular capabilities must be used so as to maintain ocular strength, flexibility, and coordination correctly. It can’t happen if the sight and its capabilities are imprisoned within a limited visual field, as happens when we view through the framework of our glasses.

Regarding the use of positive +2.5 D lenses, I must warn you that the defocus state is to be modulated and changed masterfully, depending on each type of refractive error and, above all, depending on the entity of the error itself. A –0.50 myope can use and wear positive +1.00 or +2.00 lenses when he carries out neardistant activities (so as to oppose the level of overaccommodationthat has come from viewing too-near targets). In the case of highermyopia (for example, 2 D), the accommodative state should be limited by taking off the glasses (if it’s a case of medium myopia); it’s also useful to decrease the lens dioptric power for distance viewing (negative lenses). A myope like Marco (rather high myopia)should wear undercorrection in near viewing (decrease the lens power for some diopters), or, at least, he could carry out his near-distance activities wearing his present lenses and wearing the positive additional ones (for example, a pair of –6.00 D glasses and another pair of +2.00) over the first ones. In this way he decreases the accommodation and dioptric power at –4.00 D.

The use of retinal defocus and therefore the level of the imposed defocus must be changed depending on aim: low positive lenses are to be worn so as to prevent myopia (to decrease an overaccommodative state), but for decreasing myopia gradually you must work with a higher defocus level, which couldn’t be used in ordinary activities without jeopardizing visual acuity. The defocus stimulus is aimed at stimulating a compensation for the error as well as at increasing refractive capability, and that’s why it must be temporary and limited to training sessions.

To answer your questions:

a. The results differ not so much depending on someone’s age as on the time she’s been wearing glasses (for how long a time her focusing has been “frozen” and helped with lenses, causing “disuse” or functional atrophy due to misuse).

b. It’s okay to carry out ocular stretching exercises three days per week and three times per day, but you should make your “samples” understand that muscular work at maximum ocular range must become their ordinary viewing. That’s why they must acquire the healthy habit of short ocular rotations while relaxing in the morning, like while brushing their teeth. Keep insisting on the exercises of ocular stretching, fixing at a steady point and at the extreme parts of the visual field. Do your best to make your “samples” carry out the exercises correctly, gradually increasing the rotation width and staying on the parts of the visual field where the work is very hard, due to “blocks” (at those places where muscular strength, flexibility, and coordination are limited).

c. The defocus state must be changed, increasing the dioptric power of positive training lenses, when one can read a text or letters holding the text in completely extended arms and wearing training lenses. In such a case it would be impossible to work with defocus unless increasing the training lens dioptric power.

As long as we are chronically subjected to overaccommodative stress (near-point stress) without counterbalancing it with distant viewing, it will be necessary to use positive lenses for the purpose of prevention and maintenance. Even only 1 diopter positive “leisure” lenses can prevent myopia development, when we become emmetropes.

d. The graduation for distance vision is changed depending on one’s present refractive capability and needs. Some ophthalmologists and optometrists prescribe low undercorrection. However, the limit depends on the person’s needs: if you are a driver or pilot or someone whose work requires perfect sight, you must wear full correction. If not, undercorrection works well, wearing it only when necessary for clear vision. Many people wear their glasses (or even worse, contact lenses) even when they can see clearly without them. Such a situation does nothing but worsen the accommodative balance and allow the state of chronic overaccommodation, leading to ever-higher refractive error.

Back Created by Aser srl