Freeform A reference Guide:
First of all lets understand the term freeform? Before we go back to in the history of making & inventing it
Free-form technology uses a computer assisted generator, three axis’s with diamond tips that can place whatever curved desired onto the lenses
It generates any complex designs directly with the semi-finished base between a hundredth of a dioptre.
Instead of using the traditional method of moving the knife around a single point, this generator is capable of roam around the surface of spinning lens, cut curves where necessary and how it was indicated by the computer software. Essentially, this advancement now allows labs to create completely individualized lenses.
The History:
The idea behind the power progression in one single lens with out the dividing line seen dates back to 114 years ago!!!
The first patent for a PAL was British Patent 15,735, Though never got commercialized was granted to Owen Aves with a 1907 priority date. This patent included the manufacturing process and design Unlike modern PALs, it consisted of a conical back surface and a cylindrical front with opposing axis in order to create a power progression.
While there were several intermediate steps (H. Newbold appears to have designed a similar lens to Aves around 1913), there is evidence to suggest that Duke Elder in 1922 developed the world’s first commercially available PAL (Ultrifo) sold by “Gowlland of Montreal”. This was based on an arrangement of aspherical surfaces.
The Carl Zeiss AG & Varilux lenses were the first PAL of modern design. Bernard Maitenaz, patented Varilux in 1953, and the product was introduced in 1959 by Société des Lunetiers (now Essilor). The first Varilux lenses’ surface structure was however still close to a bifocal lens, with an upper, aberration-free half of the surface for far vision and a rather large “segment” for clear near vision. The breakthrough in user adaptation and comfort, as well as peripheral and dynamic vision however occurred in 1972 with the introduction of Varilux 2, for which Maitenaz created a totally aspheric design and manufacturing process. Carl Zeiss AG developed freeform technology in 1983. Then launched with its own patented progressive series Gradal HS in 1993.
Early progressive lenses were relatively crude designs. Right and left were identical variable power lenses with distance and reading power centers in the upper and lower part of the lens, respectively. The glazing was made to accommodate eye position changes from distance viewing to reading. The point of reading is about 14 mm below and 2 mm to the nasal side in comparison to distance viewing. By tilting the reading power towards the nasal side in perfect symmetry, appropriate reading power was given to the wearer.
The symmetric design, however, was difficult to accept for patients, because the eyes in general work asymmetrically. When you look to your right, your right eye views distal (i.e. looking through the lens near to the arm of the spectacles) while your left eye views nasal (i.e. looking through the lens near to the bridge). Modern sophisticated progressive lenses are designed asymmetrically for greater patient acceptance and include special designs to cater to many separate types of wearer application: for example progressive addition lenses may be designed with distance to intermediate or intermediate to near prescriptions specifically for use as an occupational lens, or to offer enlarged near and intermediate view areas.
The typical progressive lens is produced from a so-called semi-finished lens. The semi-finished lens is molded with an asymmetrical power pattern on the front. On the back side a custom surfacing is made to adjust the power for each patient. This method is however problematic, especially for astigmatic prescriptions. The reason being that the semi-finished front pattern is designed for a spherical prescription. Freeform designs are tailored to each prescription and do not have this problem.
Since the 1980s, manufacturers have been able to minimize unwanted aberrations by:
- improvements in mathematical modeling of surfaces,
- allowing greater design control;
- extensive wearer trials; and
- improved lens manufacturing and measurement technology.
Where do we stand today?
Today the complex surfaces of a progressive lens can be cut and polished on computer-controlled machines, allowing ‘freeform surfacing’, as opposed to the earlier casting process, thus explaining the difference in price. In short, the price is based on the technology used and the year the lens came to market.
what is the Free-form process and how does it allow personalization and superior designs?
Free-form lenses are made by a process that can produce superior vision designs, but that does not mean that all Free-form lenses are great.
The Free-form process creates potential for greatness, but the lens is a great as its design, the software calculations and the measurements taken.
Even though it was first introduced for progressive users, Free-form lenses have demonstrated to also be useful for single vision users.
Today, various designs used for single vision lenses use Free-form technology in order to give the user the widest and clearest vision possible without peripheral distortions.
What do we have in Future?
The current spectrum of Free-form technology within lenses is still open and constantly growing
Progressive lens and single vision designs can be improved with Free-form technology
These new progressive designs earase every problem associated with them: lack of adaptability, peripheral distortions and vertigo.
Today, progressive Free-form offers amplitude of clearer zones where the user needs them.
Other Free-form lenses have been launched in search of personalization, including office lenses and ones used for portable digital devices.
Free-form lenses are perfect for people with active life styles, because they appreciate better optical performance and some designs are currently available in photosensitive sunglasses and even polarized options.
Every lens expert that we have talked to, as well as people we interviewed, says that the growth of these lenses is increasing within the market quota.
The lens market representatives say that within a few years, free form lenses will represent the majority of the progressive lens market, with some expecting that they represent 80% or more in sales.
Laboratories continue investing in the necessary equipment in order to produce free form lenses
So in the conclusion though traditional progressives still exists relatively because of the price segment in some developing & under developed countries.
I personally feel the free form technology are quite good and already takes consideration with the human eye and the consumers slowly adapting to the progressive lenses in their 40’s rather then the traditional progressives or bifocal lenses itself shows the ease of adaptation in a freeform progressive lenses compared to other traditional options.
In other words, if you still haven’t familiarized yourself with the conviction of recommending free form lenses, add it to your “to-do” list.
Because according to every indication, it is the lens of the future.
