It's Not Your Father's...

Two influences are beginning to have a profound affect on ophthalmic lenses. The first comes from innovative new technology becoming available for fabricating lenses in a laboratory. The second is the result of recent changes in the way lenses are distributed to the eyecare professions. Eyecare professionals should understand what's happening because these changes will impact and influence eyewear in the near future in some significant ways. Some of this evolving technology is already in place while other processes have reached beta site status and will start showing up in laboratory production lines within months.

The review of lab equipment developments that follows does not represent all new equipment and design advances, but provides a sampling to show the complexity and scope of the enhancements.

The most revolutionary change involves the basic method used to fabricate lenses. Most lenses processed in a lab start out either as finished stock lenses requiring only edging and mounting in the frame or as thick semi-finished blanks with a factory-processed front surface. Labs grind semi-finished blanks in an age-old process that basically carves or whittles away excess material, creating a new back surface with whatever curve is required to create the patient's prescription. There have been many advancements, but the basic surfacing process dates back to the 13th century.

One increasingly attractive option is a completely different way to fabricate prescription lenses. Instead of purchasing stock lenses or semi-finished blanks from major lens manufacturers, labs now have an option of manufacturing lenses by casting rather than surfacing. When they do this, lens manufacturers are eliminated altogether.

In-Office Casting: As plastic lenses became the dominant substrate in the U.S., there were attempts to adapt the casting process to making prescription lenses in a retail office. There's normally little incentive for casting single vision lenses since the savings are minimal.

When progressive addition lenses became popular, however, casting systems offered retailers substantial savings. Many retailers tried in-office casting in the early days, but abandoned the process for a variety of reasons. During the past 10 years, however, in-office casting has gone through considerable advancements.

Custom Casting By Lens Manufacturers: During the last few years, two major lens manufacturers developed sophisticated processes for casting progressive lenses individualized to each patient. These lenses can only be produced at the factory level, in effect bypassing local laboratories. Restricting the casting process to the factory level makes it possible to utilize sophisticated technology that would probably not be possible in a laboratory.

Custom Casting By Labs: Recently, two equipment companies introduced high-production casting systems designed specifically for large scale production in laboratories. A number of retail optical chain labs are now doing high production casting (mostly progressives), and wholesale labs are beginning to show interest.

Though PALs were the initial attraction, a new savings opportunity came with the development of photochromic monomers and aspheric molds. In addition, one company has developed an option for its casting process that makes it possible to apply an AR coating during the casting process.

Labs are showing interest in lens casting, but it's unlikely that casting can ever totally replace traditional lens fabrication. It will never be possible to cast glass or polycarbonate lenses, and the higher index materials will require surfacing. Current casting is limited to standard and mid-index monomers, and to the basic range of available molds.

ENHANCED SURFACING

Automation: One of the most critical and labor-intensive operations in a lab is verifying lenses after surfacing and laying them out for edging. One recent example of automation is a device that totally automates lens verification, centering, and blocking. Everything takes place in one unit, eliminating lensometers and de-skilling one of the most critical jobs in a lab. Lenses are also blocked prior to surfacing, and that operation is now available in robotic form.

In fact, totally automated processing is now available for taping (protecting front surface with tape), blocking, generating, tool picking (for fining and/or polishing), and workflow movement through the lab. It's possible today to set up a production line where the lens is never touched from stockroom to final polishing.

The Goal: In developing enhanced lab equipment for fabricating lenses, the equipment manufacturer's goal is usually four-fold: Improve quality of lenses produced, improve speed of production, reduce the required skill level of operators, and, when possible, reduce labor costs. Machines that produce higher quality optics or more sophisticated lens designs are of interest to lab owners.

To appreciate such developments, it helps to understand the traditional surfacing process currently used in labs. Step 1: Semi-finished blanks have a block attached to serve as a "handle" for subsequent operations. Step 2: The lens is then generated, taking the blank down to approximate thickness and creating the back curve required to produce the proper prescription. Step 3: The lens goes to a cylinder machine (spheres and cylinders) where it is placed over a metal or plastic lap with the same curves as the lens, only in plus form. A fining pad is placed on the lap. Fining basically smoothes the surface in preparation for polishing. Step 4: Lenses go to a different cylinder machine for polishing on a lap. Step 5: Block is removed and lenses cleaned. Step 6 (optional): Polycarbonate and most high index lenses have scratch coating applied to the back surface. Step 7: Lenses go to inspection and layout prior to edging.

Craftsmen hard at work at Sutherlin Optical's Kansas City lab in the 1950s, a far cry from today's high-tech optical laboratories. Photo Courtesy of Vision Consultants

Eliminating Fining: Several manufacturers produce generators that eliminate fining. In traditional surfacing, lenses go from generator to cylinder machine for fining or smoothing and then to a second machine for polishing. The fining operation serves several important functions. The first is to smooth the back surface prior to polishing. Curves from traditional generators have a frosted, slightly ragged surface. The back curves may also have minor optical inconsistencies, and fining eliminates those variations. Eliminating the fining operation saves considerable production time, and last year a new type of generator was introduced in the U.S. that does that. Lenses from the generator have a smooth, clear surface and can be taken directly to polishing.

This type of generator uses a single-point diamond cutter and can be upgraded to cut multicurve surfaces such as progressives, aspherics, and atoric curves. This will be a first for labs. Today, atoric or aspheric surfaces can only be produced at the factory level. Producers of this surfacing system expect that labs will be producing brand-name progressive lenses from raw slabs of plastic by 2003. A number of labs now use this generator or have one on order.

Eliminating Polishing: Another company produces a two-part system that takes lenses from the generator in part one and, using a totally robotic process, smoothes or fines lenses without tools or laps. Skipping the polish operation, lenses go to a separate unit where a scratch coating is applied.

Instead of hundreds of individual laps, less than 25 conformable laps are used. The adjustable lap conforms to the surface cut by the generator. As a result, lenses end up with a more exacting patient prescription.

Another company produces a sophisticated cut-to-coat process that consists of an integrated system of three linked subsystems: A blocker, a generator, and a coater--all incorporated into a single workcell controlled by one operator. The lenses basically progress automatically from blocker to generator to coater and come out of the unit ready for cutting and edging. No laps are used.

Direct To Polish: This new system consists of two units that take any plastic lenses (including poly) from generating to polishing with no laps. Curves are cut with a free-form lens lathe that utilizes single-point diamond turning. Conventional back curves can be produced, but labs are most excited about the ability to produce progressives lenses with progressive curves on the backside.

LENS EDGING

The most significant recent trend in lens edging has been the "de-skilling" of lens finishing. During the past 20 years, the edging process--which includes lens verification, blocking, and edging--has been automated to the point where operator errors are all but impossible. In addition to accuracy, this has lowered staffing costs and encouraged more retail offices into edging.

Patternless Edging: Most labs today use patternless edgers. The patient's frame is traced and stored in digital form. This information helps control lens thickness as well as regulating the edging operation.

Remote Tracing: Many labs now offer remote tracing to their accounts. It was slow to catch on due to inexperienced people in the doctor's office. Equipment is now available that requires no more than dropping the frame into the tracing unit, so its use is expected to soar.

DISTRIBUTION CHANGES

Lab owners are investing heavily in production equipment. One prime example is AR coating. Five years ago, few labs had the capacity to apply AR. Today hundreds of labs have made the required investment ($500,000 or more), and more are lining up to do so.

In acquiring new equipment, the first problem labs face is determining which technology will best stand the test of time.

One aspect of these options is how they affect lens manufacturers. It's obvious that any lens a lab casts in-house replaces a lens that would have been produced by a manufacturer.

	Shuron Optical's cutting machine was an early 20th century tool  Photo Courtesy of Vision Consultants

Likewise, every progressive lens produced on multi-curve lab equipment replaces lenses normally produced by a manufacturer.

It won't be a total loss for lens manufacturers, however, because some PALs produced on multi-curve equipment will use manufacturer-authorized software to produce well-known, brand-name progressives, paying royalties to the manufacturer for each lens produced.

Labs and lens manufacturers have always enjoyed a close alliance. Their traditional relationship has changed somewhat now that three lens manufacturers have set up their own laboratory networks.

Currently, it's estimated that between 40 and 50 percent of all laboratory work is controlled by these three companies, who maintain relationships with independent labs as well.

It's interesting that as some lens manufacturers become involved in lab production, independent labs are taking on some manufacturing production. It certainly is a blurring of the lines in lens distribution.

This situation also opens new door for labs. For example, atorics have been available only in stock lens form or in factory-produced lenses (primarily progressives). Now, however, labs have access to equipment that produces atoric lenses as well as customized progressives.

The result of all this is that eyecare professionals will soon have access to a wealth of sophisticated lenses that will provide visual benefits never before available to their patients. Overall, the future for ophthalmic lenses is looking very bright, indeed.