lens tips

Rimless pointers

by Karlen McLean, ABOC, NCLC

Material stress and tension are core causes of rimless lens failure, resulting in lens cracking, fracturing, chipping, or flaking. This can happen during production, mounting, or even after patient wear.

Improving rimless results by avoiding stress-induced spoilage starts with an attention to basics, and proactive production plans.

Three primary tips to better rimless production results are:

1. Use proven lens products specifically suited to rimless lens production.
2. Use extra-tough, scratch-resistant, and AR coatings.
3. Use up-to-date equipment designed for rimless production.

Industry insiders, particularly wholesale labs, cite the use of old or incorrect lens technology and antiquated equipment as the main reasons rimless jobs fail.

MATERIAL MATTERS

While all lens materials can be fabricated in almost every rimless configuration, a few lens materials are touted as especially well-suited for rimless production performance and maintaining stability. These are:

Trivex (1.53 index): Known for maximized visual clarity (Abbe 43 to 45), strength, light weight, and impact resistance, Trivex is a durable rimless option.

Polycarbonate (1.59 index): Superior strength, impact resistance, and reasonable pricing help keep poly tops in rimless production. Poly may take extra care and attention during production to achieve trouble-free results.

1.67 index: Specific 1.67 materials are developed for rimless output and durability, featuring extra-tough tensile strength that holds up well to rimless production. Asphericity and design ranges make these lenses a flatter, thinner, and lighter option.

Premium hard coatings that are durable enough to stand up to rigorous rimless processing and patient wear-and-tear are crucial to the success of each rimless job. However, these coatings can be slippery, causing the lens to go off axis. It's crucial to follow manufacturer processing tips to the letter, and use pads designed to properly secure and protect the lenses.

PRODUCTION POINTERS

Excessive clamping pressure and inflexible blocks are frequent causes of lens and coating cracking and peeling. Use an up-to-date edger that predetermines the right pressure and utilizes flexible blocks, or, if you're using an older edger, apply an appropriate blocking tape to the lens front to provide a cushion.

Don't push the drill quickly through the lenses in one motion, especially with poly. Slowly pulse the drill, which allows the material to cool, eliminating frayed exit points.

Use drill system hole placement for better accuracy and be cautious of any products that require manual marking. In addition, be sure to always factor in rimless assembly and adjustment requirements when selecting rimless styles. Confirm that lens designs can be easily achieved with your equipment.

Any assembly parts and other system necessities should be plentiful, easy to work, and fast to acquire. Use tools specifically for rimless production and fitting/adjusting. These include specialized pliers for bending, gripping, angling, and cutting without stressing drilled lenses.

Specialized tools are worth the investment considering that only one broken lens may cost at least $50 to replace. Also, make sure to have on hand plenty of parts like screws, nuts, caps, bushings, tubing, nose- pads, and anything else you need to assemble and repair rimless styles.

Half the fun of rimless is customizing lenses for each patient. Customization can differentiate your practice and bring in higher dollars for unique eyewear. EB