Trayner Technical Briefing
The lens in the eye is built up in layers, like
an onion. New layers are constantly being added to the outside,
compressing and hardening those in the centre. This results in a
gradual stiffening of the lens over time. The ciliary muscle grows
stronger to compensate for this, doubling in size between the ages
of 20 and 40. Unfortunately, as we do our close work in relatively
poor light with enlarged pupils, the eye is unable to focus as well
as it might and the ciliary muscle does not get as much exercise
as it needs. The growth of the ciliary muscle falls behind what
is required for the closest focusing. This ‘near point’ gradually
moves further away until by the mid-40s it starts to interfere with
reading small print. This is called presbyopia. The conventional
treatment for presbyopia is to place a lens in front of the eye
to add the extra focusing power that the eye is unable to provide.
This immediately brings print into focus but also leaves the ciliary
muscle less work to do. With habitual use of reading glasses the
ciliary muscle gets less exercise and starts to get weaker, further
reducing the ability to focus close up.
What to do about Presbyopia
The ciliary muscle needs more exercise rather than
less. It is not under conscious control so we have to find a way
of encouraging the eye to focus itself more fully. The answer is
to provide an artificially small pupil (a pinhole) in front of the
eye, to help the focusing system work more fully. This is the principle
behind Trayner pinhole glasses. These have an array of small holes
through black screens that replace the lenses in a pair of glasses.
By reading with the aid of Trayner pinhole glasses for fifteen minutes
or so every day, the ciliary muscle is exercised and grows stronger.
Vision is clearer while using Trayner pinhole glasses because the
ciliary muscle and lens are focusing beyond their habitual range.
The unaided vision improves gradually over a few weeks as the muscle
gets stronger with the extra use.©Peter Duthie 1998/2000