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Tuesday / June 25.
HomemiequipmentIn-House Lens Processing (Part 2)

In-House Lens Processing (Part 2)

Last month we explained how the integration of a finishing lab may provide you with the means to both control costs and improve service to your patients. By providing patients with the same dependable quality of care, it is less likely that they will take their prescriptions with them when their exam is completed. In Part 2, we explain exactly what to look for in an edging system.

When making a decision on the purchase of an edging system, it is critical to consider the individual needs of your practice. The highest lab costs incurred by most practitioners are for orders that require special edge treatments, grooving and drilling. These functions are no longer performed manually by highly skilled dispensers and technicians in the local lab, but by the high-tech edging systems that they utilise.

Gone are the days when one individual alone in each lab was capable of providing a high-quality finished product that was worth the added costs.

Today, many labs still charge the same high price for the grooving, polishing or drilling, but add considerably to their own bottom line by having modern edgers to do the intricate detail work for them.

The real benefits of the high-tech finishing lab are in not only providing eyewear at a reduced cost, but also having the ability to provide better customer service and turn-around time

This is not to suggest that anyone can operate the equipment, but it also doesn’t take a ‘rocket scientist’ or master craftsman.

In the past, edgers depended on patterns and sizing mechanisms to attempt to edge a lens to the proper shape and size. We were forced to calculate an edger setting size and were also sometimes forced to make patterns for frames that they didn’t have a pattern for.

The use of handmade patterns often led to both sizing and shape problems that also resulted in improper placement of the lens centres or segments. Modern edgers solve this problem in two ways; automatic tracing and computerised centring.

Be sure to carefully review the capabilities of any edging system in these two areas before you make a purchase.

The edger should be capable of high-precision binocular tracing, capturing the profile, angle and bevel shape. This 3-D tracing not only establishes the shape and circumference, but should be able to store up to 200 individual shapes in the edger’s memory for later use. It should also be able to trace frames of any material or style, including half-eyes and frames with small ‘B’ measurements. It accurately calculates the distance between lenses (DBL), ‘A’ and ‘B’ measurements and stores that information for use in the lens centring process that follows.

The touch screen of a modern system should allow the operator to input monocular pupillary distance measurements as well as segment heights or other required vertical centration information.

The display of at least one edging system will then utilise a unique automatic centring function to take over. Using a video analysis system, the lens requires no specific orientation in the blocking chamber.

A single vision lens is analysed for sphere, cylinder and optical centre and the axis that has been input is aligned automatically and presented for your view. The image is aligned with the traced frame shape and a lens diameter recognition feature confirms that the lens is large enough to cut out. The system can also recognise and automatically centre curved and straight top bifocal segments and a number of commonly used progressive addition lenses. In a seamless process, the tracer should be able to automatically block the lens, with the block applied relative to the identified axis. Be certain that the blocking mechanism is capable of half-eyes and frames with small ‘B’ dimensions with blocks of different diameters to meet the needs of frames of all types and shapes.

For high-index materials, especially those with AR treatments, another important feature is the ability to control chuck pressure to avoid damaging surface coatings. Some edgers are provided with sophisticated software that allow for individual material cycles that adjust the feed and speed of the wheels and adjusts the lens chucking pressure, taking the shape and thickness of the lens into consideration when adjusting these parameters.

Bevelling Options

Automatic bevel selection allows the machine to edge the lens by calculating optimal bevel placement from furnished data. In addition to standard bevel, rimless and grooved edges, a number of customised bevel options should be available. Any modern edger should be capable of processing all commonly used lens materials, including glass, plastic, mid-high index, Trivex and polycarbonate lens products.

The machine should be outfitted with size and shape modification software that will allow the operator to modify the lens proportionately in all dimensions, change half of the ‘B’ measurement, all of the ‘B’, or at any single point prior to blocking the lens.

Shape modification capabilities should include the ability to allow modification before or after centring. Modification before centring would allow the operator to adapt a drilled or nylon shape to suit a patient’s face or taste, while modifying after centring would allow the operator to adjust the shape to optimise multifocal segment placement.

A pin bevelling feature will eliminate the need for the manual process that has been a source of problems for years. You can avoid sizing and shape errors, providing quality and consistency in edge treatment while improving the lens’ cosmetic appearance.

Grooving, the process of cutting a channel of a specific width and depth between the front and back surfaces of a rimless lens is another important consideration when choosing an edging system.

The nylon rimless mounting is very popular today and it is extremely important to assure that the lens is securely mounted in the frame. Patients are generally not very happy when they have their lenses constantly falling out.

Controlling placement of the groove is critical, as is adjustable groove width and depth capability. Better edgers trace curves of both surfaces of the lens being cut, and the curvature of the frame to precisely locate grooves on even very thin lenses.

The newest feature of some modern edging systems is the integration of lens drilling. Some of today’s frames have mountings that require drilled holes, notches or slots in order to affix the lenses. The features to look for include:

a. drill co-ordinate uploading and storage capability

b. stored co-ordinates should be able to be applied to other shapes

c. edger should be OMA compliant for uploads and downloads of data

d. capable of photographing demo lenses and drill hole locations for matching

e. allows tilted drilling angle to assure the hole is perpendicular to the front surface of the lens

f. easy to interchange drill bits

g. provides drill modes and cycle times for each individual lens material

h. through and non through holes

i. straight or angled notches

j. vertical, horizontal or angled oblongs

k. manual option for drill co-ordinate modification

The wide range of features available in 21st century edging systems has made the job of fabricating eyewear easier and much more accurate. In order to insure continuing accuracy it is important to maintain and calibrate the equipment on a regular basis and even that can be a built-in function of the edger. Automatic sizing calibration and wheel cleaning are a must.

Select, Don’t Settle

The decision to incorporate finishing into your practice or to update the capabilities of your finishing laboratory is a rather complex one. If you take the time to carefully research the abovementioned features, you will quickly realise the benefits they have to offer and ultimately that should be reflected in increased profits.

The real benefits of the high-tech finishing lab are in not only providing eyewear at a reduced cost, but also having the ability to provide better customer service and turn-around time. You need not be dependant on your lab to provide services that are currently costly and tend to take more time than should be necessary.

Do the research, take an edger system for a ‘test drive’ if possible and be sure to go with a list of capabilities that are right for you.

Geoff Marett has 37 years experience in the optical industry and began his career working as an optical mechanic for Sola Optical. He has worked at Gerber Coburn for the last 23 years, as the Director of Technical Services and Sales Engineering and now, Director of Sales.