Comparison of Progressive Lenses. Evolution of Lens Designs. The Jury is In 2/11/2011. Copyright 2006, Phernell Walker, II, AS, NCLC, ABOM 1

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1 Comparison of Progressive Lenses Evolution of Lens Designs There s been a quiet revolution in progressive lens design over the past 32 years. Phernell Walker, II, AS, NCLC, ABOM Master in Ophthalmic Optics We ve come along way from lenses of yester year to remarkable lenses that patient s love. 1 2 The Jury is In The jury on progressive lens designs is in! and the WINNER IS: Digitally Surfaced Lenses WHAT IS A DIGITALLY SURFACED LENS? Free form lens surfacing allows the placement of complex, nonsymmetrical optical surfaces directly onto lens blanks one lens at a time May be described as Direct Surfacing or, Digital Surfacing Produces progressives, and aspheric and atoric single vision lens designs 3 ENABLING TECHNOLOGY Free form allows for the production of more sophisticated lens designs with extensive customization for the wearer one lens at a time Improved designs with no compromises Improved designs with no averaging Improved lenses with fewer defects -Free-form lenses are cut with an accuracy within 1/1000th of a mm. EFFICIENCY Free form can offer various manufacturing efficiencies one lens at a time No costly inventory sitting on a shelf - just in time manufacturing Create the lens as needed -Never out of stock ABOM 1

2 HOW ARE FREE-FORM LENSES CREATED? The lens surface may be generated using a three-axis, computer numerically controlled (or CNC) generator THE PROCESS With three possible axes of movement, single-point cutting tools can produce virtually any lens surface shape with a high degree of accuracy and smoothness UP CLOSE The worked lens surface is then polished to a high luster using a flexible polishing pad that is also dynamically controlled by a computer WHY IS FREE FORM MANUFACTURING BETTER? Traditional, Semifinished Lens Manufacturing Mass production process that imposes significant development costs and inventory requirements, particularly for progressive lenses Limits innovation and improvements WHY IS FREE FORM MANUFACTURING BETTER? Traditional, Semi finished Lens Manufacturing A typical progressive lens design must be adequately stocked in up to five different base curves, 12 different add powers, and a wide variety of lens materials per eye. Increases opportunity for error when selecting a lens at the lab level Leads to problems at the dispensing level SEMI FINISHED LENS MANUFACTURING Consequently, semi finished progressive lenses must be designed for the so called average spectacle wearer Results in a variety of optical compromises for many wearers as results are tailored for broad categories of wearers - not customized Ophthalmic professionals must learn how the averaged lens performs and often are forced to compromise their recommendation based on best overall fit ABOM 2

3 FREE FORM LENS DESIGNS Allows optical laboratories to produce more complex, customized, asymmetric lens designs on demand without the extensive inventory limitations of traditional semi finished lenses Some of these designs would be: Back surface progressives; enhanced vision FREE FORM LENS DESIGNS Free form is an enabling technology; it does not guarantee customization May be used simply as a substitute for traditional semi-finished lens surfacing The design must be sophisticated to produce premium results Longer corridor progressives; slow rate of peripheral astigmatism FREE FORM TECHNOLOGY & LENS DESIGNS Real time customization based on Use; lifestyle activities Prescription Position of wear The "best customer for the best lens approach through customization FREE-FORM WHEN A SOPHISTICATED OPTIMIZATION PROGRAM IS EMPLOYED 1. The program begins with a base design 2. The base design can be morphed, modified, or selected based on patient data to arrive at the actual target design The prescription and ergonomic parameters are then entered in to arrive at an initial progressive lens model 3. This initial lens model is analyzed using optical ray tracing for the as worn position 4. The software then minimizes merit functions (such as optical blur) between the ray-traced lens model and the original target design across the entire surface A final lens is arrived at, representing the best performance for the individual wearer Note: A compensated prescription is supplied for certain free-form progressive lenses in order for eye care professionals to Verify the prescription using a standard focimeter LIFESTYLE CUSTOMIZATION BIOMETRIC ANALYSIS Progressive lens designs can also be selected or even individually customized based upon biometric analysis of the wearer using head tracking systems CUSTOMIZATION BY LIFESTYLE ANALYSIS Progressive lens designs can be selected or even individually optimized based upon an assessment of the particular visual demands of a given wearer PDA Dispensing Tool ABOM 3

4 The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again. 2/11/2011 LIFESTYLE: VARIABLE LENS DESIGNS A starting baselens design can be manipulated to maximize certain optical attributes for a given wearer, such as the size of viewing zones PRESCRIPTION OPTIMIZATION Customization refines the optics of the lens design using complex aspherization to deliver the intended performance for any prescription None of the compromises found in semi-finished base curves Distance Enhanced for Driving Balance d Design Near Enhanced for Close work Ideal Performance Actual Semi-Finished Optimized Performance Plano Rx, Add Lens Performance FREE-FORM OPTIMIZATION PROCESS WHY FRAME STYLE CUSTOMIZATION? Step 1: Base Design x 045 Step 2: Modified Target Wearers choose different frames and have varying pupil heights and physiology. This affects the amount of reading area available in their frame. Conventional S/F PALs attempt to solve this problem with regular and small frame PALs. That s fine for patients with fit heights exactly matching the design sweet spot. Step 3: Ray-Traced Rx Step 4: Final Lens No conventional S/F lens can be optimized for performance at all fitting heights and all frames. VARIABLE CORRIDOR LENGTH MORPHING TECHNOLOGY Fitting Height ranges from 13mm to 35mm* EVERY FRAME DELIVERS FULL READING PERFORMANCE NO FORCE FITS, NO COMPROMISES 13mm 15mm 21mm 17mm *Above 20mm the corridor length is set by physiological ergonomics ABOM 4

5 2/11/2011 IMPROVED VISION: DISTANCE Simulated field of acceptable binocular vision across a ±30 field of view at distance A fully optimized free-form lens can provide considerably larger viewing zones Example: Fully Optimized Free-Form Conventional Semi-Finished INCREASED PATIENT SATISFACTION PRACTICE BENEFITS OF FREE-FORM LENSES Patient retention - satisfied patients lead to referrals Differentiate your practice - expertise to take more complex measurements; provide superior products Increased sales - higher average selling price; referrals IMPROVED VISION: NEAR Up to 50% larger viewing zones for many Rx s Example: Fully Optimized Free-Form Conventional Semi-Finished Simulated field of acceptable binocular vision across standard page at 40cm INCREASED PATIENT SATISFACTION Comparison of Progressive Lenses Phernell Walker, II, AS, NCLC, ABOM Master in Ophthalmic Optics 30 ABOM 5