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Cast-Molded Eye Glass Lenses

Posted May 20 2009 10:17am
I recently heard from a couple of old friends back from my contact lens days. They are starting a new company to produce ophthalmic lenses in an eye care professional’s office. I had done some consulting work on in-office plastic lens molding in the early 1990s and had also studied the high-index plastic lens business. I wrote about one of the innovative in-office lens molding companies in an OSN Technical Update column in 1993, and my friend was wondering if I still had a copy of the column.

I managed to find the column I had written on my old computer, and since my friends were developing a new company based on this type of process, I decided to reproduce the original column as it relates the history of in-office lens casting.

As a salute to my old friends Tim Rogers and Steve Martin, and their new company QSpex Technologies and its Lens Transformation Process, here is what I wrote about Innotech and its Excaliber lens molding system back in the March 15, 1993 issue of Ocular Surgery News.


TECHNOLOGY UPDATE

The Excalibur SurfaceCasting System from Innotech: "He who has the sword shall be King!"

Irving J. Arons
Ophthalmic Consulting Group
Arthur D. Little

Over the years, several groups of innovative people have attempted to bring techniques for making "instant" ophthalmic lenses in the office or dispensary to market. These attempts reached their peak about five years ago with the advent of LensCrafters' advertisements for "1 Hour Service".

Since the LensCrafter claims to make most Rxs in about an hour were based on having an in-store processing lab, to stay competitive both independent dispensers and other chain retailers explored the options for making "fast" lenses offered by the likes of Vision Sciences and Technavision, the then (barely) surviving in-the-office lens casters.

Technavision, originally known as Orplex, was born in 1982, while Vision Sciences came along a few years later. And then there is Henry Earle, the grandpappy of lens casting, with his Duralens process, which was started in the early 1950s. Later on in 1988 Larry Joel developed his "Fast Cast" system, which he sold to Pearle Vision allegedly for $25 million. Pearle is still working to get the bugs out of the system before releasing it to its retail outlets.

Along the way, both Henry Earle (in about 1985) and Norman Rips, perhaps a year or so later, each developed wafer bonding methods -- the gluing of a thin lens carrying the Rx and/or bifocal correction onto a base stock lens. The Rips' system, originally called the Krom-X process, is now known as the Dicon Instalens process and is still being sold, now by Dicon/Visimed (San Diego). And other wafer systems are being developed by such as Tandem Optics (Rochester, NY), Pentax (Japan) and Sola Optical (Petaluma, CA).

Now, a new company, Innotech (Roanoke, VA), founded by Ron Blum and a group of people formerly associated with Vision Sciences, have come up with a hybrid technology, half way between the old thermal cast molding technique and the newer UV adhesive wafer technology. It is called SurfaceCasting using the Excalibur Office-Based Lens Fabrication System.

This patented process involves a single glass mold -- with either a progressive or flat-top 28 design, a proprietary, thin CR-39-based backup wafer (single vision lens) or Power Plate as the company calls it, a specially formulated CR-39 liquid monomer containing UV curing initiators, and a UV curing apparatus.

In use, two flat-top or progressive molds are placed into a holding tray, about a teaspoonful of the monomer is added to each mold, and the appropriate power plates positioned on top. No gaskets or pressure holding devices are used. The sandwiches are placed into a small UV curing chamber polymerizing the resin which bonds to the power plate backup wafer (back surface of the lens), and assumes the shape (and power) of the mold surface (front lens surface). This resin polymerization process takes about 27 minutes. The cured sandwiches are then placed into a demolding apparatus which separates the finished lenses from the molds in about two minutes. The whole process to produce a pair of bifocal or progressive lenses, including selection of the appropriate molds and wafers, assembly, curing, and demolding, takes about 35 minutes.

According to industry experts from LensCrafters and Texas State Optical who have observed the process close up, operating the system at three beta sites each, the system produced first quality, thin lenses (that the company claims exceed ANSI lens standards) at affordable prices. Innotech claims that the new UV processed lens is about 20% harder than conventional CR-39 lenses and therefore may not require a scratch-resistant coating. Innotech further claims that lenses made using the technique can save a dispenser an average of about 65% of the cost of buying progressive lenses from a lab, and about 35-40% of the cost of typical flat tops. (In the company's calculations, this worked out to about $15 per pair versus $45 for unfinished 75mm progressives and $12 versus $18 for the 75mm flat tops.) Further, the finished lenses can be hard coated, tinted, and anti-reflection coated similarly to standard CR-39 lenses.

For now, a series of 108 core molds can be obtained to make either flat-top 28s (54 molds) or their proprietary progressive design lenses (another 54 molds), with spherical powers from -4.00D to +4.00D, cylinder powers of -0.25 to -2.00D, and add powers of +1.00 to +3.00D. The progressive lens design is a "semi-soft" style according to company executives.

As noted, the system has been beta tested for a minimum of three months at seven sites, including three LensCrafters and three Texas State Optical retail locations. It will sell for approximately $32,000, plus an additional $3000 for an initial supply of monomer and a customized inventory of power plates depending on the practice size and lens type usage. The price includes two days training, service and a one-year warranty. The company claims the system is capable of producing up to 12 pairs of multifocal lenses per day, and that a typical dispenser using the Excalibur SurfaceCast System to produce 6-8 pairs of multifocals per day would pay for it in less than 2 years.

The Excalibur is self-contained with a microprocessor control unit, built in resin dispenser (and reservoir), curing chamber, and mold and wafer inventory holding drawers.

For those interested in seeing the system up close and personal, it will have its first public demonstration at Vision Expo in New York city at the end of March.


A number of question remain to be answered:

● Will high-index resin material and back up wafers be available any time soon to produce high-index lenses?

● The company claims to be able to produce "thin" lenses. How thin is thin?

● What is the life time of the molds? For how many cycles can they be used? What is the cost of replacement molds?

● What is the real cost per lens pair when labor, mold replacement, cleanup and other miscellaneous costs are included?

● What is the yield of high quality lenses? How much breakage/spoilage can be expected over a years usage?

● What skills are required to run the system? Can a lab tech run it, or is special training/education required?

● Will proprietary progressive lens designs such as Varilux be made available in the future?


The company's R&D plans are to extend the SurfaceCasting technology to include production of IOLs, bifocal and toric contact lenses, and consumer and aerospace optics in the future.

Although our initial impression of the system is that it appears promising, perhaps even "revolutionary", as with all things new, only time will tell if this "better mousetrap" will conquer the world (i.e., "He who holds the sword", etc.). But, with the announced initial sales of over 135 systems to LensCrafters and TSO, the company is off to an auspicious start!


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