DIGITAL TECHNOLOGY
What is free form?
It is a more accurate method of creating a lens surface. Conventionally surfaced lenses use a fixed curve lathe to create simple surfaces, then go through multiple stages of fining and polishing to create the final optical surface. In order to create a progressive addition lens, the design has to be molded on to the front of the semi-finished lens blank. This limits the fluidity of the design in matching it to a specific patient’s needs, and restricts materials and corridor lengths. Free-Form lenses are made using advanced computer controlled generators that can create any complex surface. This complex surface can incorporate far more information allowing more advanced and personalized designs. Additionally, there is only one polishing step necessary to create a perfect optical surface, so the integrity of the design is maintained throughout the whole process. This higher level of accuracy is what has allowed for the rapid advancements in lens design. The question follows…
What is now possible with this new level of accuracy?
Position-Of-Wear Compensation
When a patient is refracted behind a phoropter, they are looking through flat lenses without any pantoscopic or panoramic angle. Since no pair of glasses dispensed actually fit that flat, in order to create the lens accurately the prescription must be compensated for the angle of vision through the lens. Free-Form lenses make it possible to incorporate the precise angles and positions of the frame to compensate the prescription to the specific frame and eye system.
This gives you the sharpest vision possible straight ahead.
Global Design Technology
Most lenses are only accurate for one point and diminish in performance as the eye rotates away from the center. This is because different angles of vision through the lens creates astigmatism. By incorporating the position of wear measurements and using advanced computer modeling programs, it is now possible to create a lens that corrects for the astigmatism as the eye rotates into the periphery.
The provides the best possible peripheral vision.
