Free-form lens technology uses digital-point technology, which means each and every point on a lens can be unique.
The old way of grinding lenses …
The resulting lens surface contained elliptical errors and was not optically clear. It required a two-step process, known as fining and polishing, to make the lens ready for use. These processes removed somewhere between 2/10 and 4/10 mm of material from the lens and had significant associated costs. They also required selecting a corresponding plastic or metal tool called a "lap." A surfacing laboratory required a lap for every possible curve that could be ground. The basic inventory of laps needed was approximately 2,000.
By comparison, free-form technology uses digital-point technology, which means each and every point on a lens can be unique. Point technology generators use a router bit-type tool guided by a computer program. During the grinding process, the spinning bit and lens move in the grinding chamber. The result-an optical surface that can be both atoric and aspheric, or simply spherical or toric if desired. Simply put, it is now possible to alter the surface geometry of a lens in extremely sophisticated ways.
What makes free-form technology so promising is that the digitally generated curves can be extremely sophisticated. Aspheric/atoric designs, such as progressive lenses, are easily attainable because the surface geometry of the lens can be altered in nearly limitless ways. As a result, the design parameters of a progressive lens-such as corridor height/width, and reading area height/width-can be varied to meet the unique visual task requirements and lifestyle needs of individual patients. This is in contrast to conventional progressive lens design and marketing, where most progressive designs are molded on the front surface and the laboratory grinds the back of the lens using the non-free-form technology described above.
Beyond this, because the curves created by digital-point technology are extraordinarily true and the resultant back surface almost optically clear, the fining operation can be eliminated. In addition, polishing the lenses takes just about a minute and removes only a few µm of material. This results in savings of manpower, equipment, and materials. More importantly, off-power rejects are dramatically reduced, thereby increasing production yields and improving profits.
Equally important-the lab doesn't need the 2,000 laps required for conventional surfacing, nor does it face the inherent error when a technician picks the wrong lap. Digital surfacing uses six soft, molded tools, which are selected to meet the digital surfacing equipment.
What's in it for you
How will free-form technology affect your dispensing practice and your patients?
In the very near future, you will be able to offer your patients progressive lenses that are custom designed to their specific set of visual task requirements and lifestyle needs. You and your optician will literally be able to specify the parameters of the various portions of the lens. This will greatly diminish patient rejects and non-adapts due to improper lens selection by the optician, something that occurs often when an optician dispenses the same one or two brands of progressive lenses to all their patients.
Software and hardware is being introduced to the U.S. market that will allow smaller labs to manufacture and offer their own brands of progressive lenses to you. If successful, and the current wrangling over patent rights can be worked out, the increased availability of progressive lens products should create the kind of competition that drives wholesale prices down.
What can you do to keep up-to-date on new developments in the free-form lens arena? Read optical industry trade journals and stay in touch with your outside laboratory vendor. That way, you'll be ready to take advantage of this technology as soon as it becomes available to you.
Arthur De Gennaro is president of Arthur De Gennaro & Associates LLC, an ophthalmic practice management firm that specializes in optical dispensary issues. De Gennaro is the author of The Dispensing Ophthalmologist. He may be reached at 803/359-7887, firstname.lastname@example.org
, or through the company's Web site, http://www.adegennaro.com/.