Free-form lenses can provide patients with better vision and improve the quality of their life.
Today’s computerized lens manufacturing equipment can create virtually any lens design, allowing for more exact prescriptions and compensating for higher order aberrations such as spherical aberration. Lenses can be manufactured to 0.05D as opposed to 0.12D in the past. As doctors, we need to know how to apply these new technologies to solve patient problems.
HOW it WORKS
In digital surfacing or free-form technology, computer software directs a needle-like blade to cut a point on a lens, giving that part of the lens specific focusing properties. These “points” can be thought of as an area where a “light ray” passes through the lens and is focused on the retina. The light rays can now be focused differently depending on what part of the lens it passes through. For example, the center of the lens would have a different focusing point than the far periphery, thereby reducing distortion.
Initially digital surfacing was used for progressive addition lenses. Now it’s used to also cut the distortions and improve vision on single vision lenses.
THE PATIENT ANGLE
Patients don’t need to know the exact free-form process, but they do need to know new million-dollar machines can manufacture lenses better than ever before, allowing for correction of distortions caused by lens optics, congenital eye conditions, the aging process, or eye disease.
These million-dollar machines were first only available to the lens manufacturers. They are now being purchased by optical labs, allowing the finished glasses to get to the optometrist faster than when they had to be shipped to the lens manufacturer for processing then shipped back to the lab who then shipped them to the doctor. In addition, there is now equipment for retail operations.
TYPES OF LENSES
Most lens manufacturers have lenses that are digitally surfaced on one side, while others have them on both. One-sided digitally surfaced lenses include Shamir Insight, Inc.’s Autograph II® and Signet Armorlite, Inc.’s KODAK Unique. Essilor of America, Inc. also offers Varilux Physio DRx™, Varilux Comfort DRx™, Varilux Physio Short DRx™, Varilux Comfort Short DRx™, Essilor Ideal, Ideal Short, and Ideal Advanced.
Another back-surface digitally surfaced lens is Carl Zeiss Vision Inc.’s ZEISS Individual™, which features Precise-Form™ Technology. By combining precision diamond-cutting tool placement, patented technology, and polishing control, Precise-Form Technology delivers consistent form and power across each lens surface.
Two-sided digitally sur-faced lenses include Essilor’s Varilux Physio Enhanced™ with W.A.V.E. Technology 2™, DEFINITY®, DEFINITY SHORT™, Varilux 360 Progressives (Physio 360), Varilux Comfort Enhanced™, Varilux Physio Enhanced Fit™, Varilux Physio Enhanced eyecode™, Varilux Ipseo IV™, and Varilux Ipseo IV eyecode™. Also available is HOYA VISION CARE, North America’s iD lens series.
Digitally surfaced lenses are available in a host of other designs, including anti-fatigue lenses, computer lens designs, and variable focus lenses. Myriad ocular conditions, from keratoconus and pterygium to macular edema and age-related macular degeneration, can also benefit from the precise optics these digitally surfaced lenses can offer.
Peter G. Shaw-McMinn is assistant professor at Southern California College of Optometry and senior partner of Sun City Vision Center in California.