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News » VARIFOCAL LENSES, YES OR NOT?
VARIFOCAL LENSES, YES OR NOT?
A nice lady, which later became our satisfied customer, a while ago sent us an e-mail, which we publish in full, together with our response in the hope it will help those who are considering adopting, for the first time, varifocal lenses, also known as progressive lenses.
"Hi, I\'m Gina, I am 49 years old. I have been using glasses for 12 years and a while ago, in addition to not being able to focus on distant objects, I started having problems to focus on objects close to me.
I consulted my ophthalmologist who told me that I had two choices: 1. use two pairs of glasses; one to see far and one for reading. Obviously I would have had to keep changing from one pair to the other.
Option 2. Was to go to my optician and ask him for one single pair of glasses with VARIFOCAL lenses; useful to focus on near, intermediate and far objects. In short FOR ALL DISTANCES.
My eye doctor further advised that since I had never used varifocal lenses, I might have some problems of adaptation.
What can you tell me about it to reassure me? "
Thank you. Gina. Padua (Italy)
The following was our reply to Mrs Gina.
Your ophthalmologist has exposed very clearly the problem: those who have never worn glasses with progressive lenses, have, in most cases, an initial difficulty in getting used to the new lenses.
Why this difficulty?
Because the brain has to "get used" to see through the various areas of the progressive lens.
We try to make it simple:
When using a standard single-vision lens, almost the entire surface of the lens corrects your vision in the same way: it means, the correction area is very large and there is no need to move your head to see through the glasses; it is sufficient to move your eyes.
When using PROGRESSIVE lenses (or Varifocal, which is another name for the same type of lens) , the Lens Correction area is reduced because the lens is divided into what, using simplified terms, we call THREE AREAS.
The upper part of the lens is used to look away, the central part is used to look at intermediate distances, while the lower part of the lens is used to read or work at close distance, all connected with continuity of vision (hence the name progressive lens).
That\'s why The "focusing system" by the user, must change.
The user, must not move their eyes but must get used to move THE HEAD.
This is the reason why it takes time to get used to the new way of looking.
The amount of time needed varies from individual to individual.
We would like to reassure you, however: young people (49 years old is a young age), generally do not take a long time to get used to the new lenses (a few days at most).
The brains of young people reacts instinctively to new lenses resting on the nose, and in any case, the small initial problems, largely compensate for the fact of not having to use two pairs of glasses.
Our long experience has taught us that some older people, say from about seventy or older, have obvious difficulties to get used to progressive lenses. This is because their brain has been used for too long to "look in a certain way”, and find it difficult to adapt to the a different way of looking though progressive lenses.
Further, dear Gina, we would like to give you a little more information about progressive lenses.
Here follows some historical / technical information about the progressive lenses, which is deliberately written in lame terms, for not wanting to get too technical.
The first progressive lenses (first generation lenses), were marketed in 1950 but only around 1958 they become relatively common.
It must be said that the first progressive lens, compared to those available today, were quite "primitive."
The progression of power of these lenses was made in the front face of the lens and there was almost no intermediate focusing area. The focus went, quite brutally from far to near.
To look through them, created severe aberrations (distortions), especially in the near and to the sides of the lens, and it took a lot of brain training to adjust to the distortions that the eye transmitted to the brain.
Since 1972 the technological evolution in the optical field, introduced progressive lenses market as “second generation” which were made with evolutionary conic sections, and gave, for the first time, a true focusing power of the progressive kind.
These lenses, though improved, were still far from being used on a large scale, firstly because there was a natural reluctance on the part of opticians to recommend to their customers "something that still gave a lot of problems" and also because the knowledge and equipment for their correct assembly were scarce.
We had to wait until 1980 to see on the market the first asymmetric progressive lenses that finally corrected the defects of near vision, as well as those at intermediate distances.
Since then, the main suppliers in the world of lenses have continued (and continue) research.
Today, progressive lenses available to the public, compared to the poor sisters of 1950, seem science fiction.
The most significant change, took place a few years ago, when the first FREEFORM PROGRESSIVE LENSES - INTERNAL GEOMETRY were created.
What does it mean Internal Geometry?
Simplifying to the maximum: to manufacture a lens, we start from a disk (cylinder) of plastic material or a disk or mineral glass. This is inserted in a computerized machine which removes the excess material to create the lens according the desired prescription.
The old progressive lenses (still available on the market) were “grounded” on the outside, while the new internal geometry lenses, are grounded on the inner face, that is, the one closest to the eye.
What difference does it make?
The difference is that the correction offered by the lens, taking place closer to the eye, is much more effective and accurate.
Furthermore, even the techniques and equipment used to cut and assembly the lenses in their correct position inside the frame, have gone through enormous progress.
Today, every single progressive lens is ordered, manufactured, cut and mounted on the very exact and individual prescription of each customer.
There still are, on the market, cheap progressive lenses, offered, "over the counter" - ready to use.
We want to stress that the variables related to the construction of a progressive lens are so many that they MUST be built with "the prescription in hand". For this reason, delivery time of progressive glasses, are necessarily longer opposed to single-vision specs, which, in many cases, are made with lenses ready in stock.
We want to add that progressive lenses, as well as single-vision lenses may also be colored to make them into prescription sunglasses. Or they can also be Photochromic Transition, ie lenses that pass quickly from light to dark depending on the lighting conditions of the sun.
A nice thing to have because with a single pair of glasses, one can cover a full spectrum of needs.
A brief final chapter about the costs.
FREEFORM PROGRESSIVE LENSES - sold by us, are not to be confused with the old generation of lenses still offered by some optician in order to keep prices low.
Old fashion progressive lenses are cheaper but DO NOT offer the same comfort of vision. So, always make sure what you get for the price you pay.
All the best from.