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Design of Occupational Lenses
Progressives / Alternative Multifocals
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Jon Torrey VP, PRIO/Computer Vision Essilor of America
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Background
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Fundamental Shift in Use of Vision
Past: Primarily distance vision Today: Intermediate/ near
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Computer Use by Presbyopes
Continues to increase: Number of individuals Hours/week/individual
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Computer Use by Presbyopes
Driven largely by specific applications: Social networking sites
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Computer Use by Presbyopes
Baby boomers: 1st generation to use computers through majority of career Continuing use into retirement
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Computer Use by Presbyopes
Nature of Presbyopia: Loss of Accommodative amplitude Necessitates a reliance on lenses to enable clear viewing at intermediate and near distances
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LCD / Widescreen Displays
Rapid acceptance of technology has compounded the need for improved intermediate viewing, and specifically wider intermediate areas within lenses
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Optometrists’ Quotes “Up until now I basically gave up on these patients that have visual fatigue symptoms. I didn’t feel like I had anything to offer them in my clinical arsenal.” “There really isn’t enough products for us to pick from for dealing with some of these accommodative disorders that we’re identifying.” “The progressives don’t cut it for those patients who spend great deals of time on the computer.”
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Current Lenses: Design Limitations
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Current Lens Designs: Limitations
Given nature of intermediate viewing at 50 – 70 cm, current lenses available are less than optimum: SV – when set up for intermediate distance, no facility for more plus at near No clear viewing at full distance
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Current Lens Designs: Limitations
Bifocal – when set up “normally,” no clear area for intermediate distances Typical response is for wearer to tip head back and lean forward
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Current Lens Designs: Limitations
Bifocal – when set up for intermediate distances, with a small add for near viewing, wearer sacrifices clear distance vision
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Current Lens Designs: Limitations
General-purpose PAL: intermediate area is 3rd priority, after Distance and Near Intermediate area is narrow and located below center, requiring head tipping to see desktop screen clearly
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Current Lens Designs: Limitations
Near Variable Focus lenses: significant step forward in visual flexibility and comfort Many wearers still request full distance vision
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Research – Design Preference
Patient preference in lenses for computer use, comparing general-purpose PAL with Near-Variable Focus design 97% of subjects preferred NVF design (Essilor, 2004) 81% of subjects preferred NVF design (PRIO, 2004) 1) Source: Essilor of America – Lens Comparison Survey - October ‘04 (40 subjects ages 45+) USA 2) Source: PRIO Corporation – Lens Comparison Survey - August ‘04 (40 subjects ages 45+) USA
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Computer/Intermediate Lens - Ideal Design?
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Ideal Lens: Design Factors
Feature set for ideal “occupational” lens for extended intermediate and near viewing would of course be a tradeoff between a variety of factors: Vertical placement of intermediate power Width of intermediate area Slope of power curve
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Ideal Lens: Design Factors
Percentage of prescribed add power delivered at fitting cross Corridor length Area of full distance power at top of lens Minimum B measurement required
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Ideal Lens: Delivery Factors
Just as important as the optical design factors are the “delivery” issues: Rx prescribing requirements for Doctor (distance, intermediate, or near Rx?) Fitting parameters for dispenser Ordering information needed by lab
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Essilor ComputerTM An Ideal Compromise
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Essilor ComputerTM Design
Maximize intermediate area, both horizontally and vertically
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Essilor ComputerTM Design
Accommodate ergonomic needs of majority of wearers Screen ~60 cm ~4° ~30° ~30 cm ~45 cm Keyboard
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Essilor ComputerTM Design
AScalc [WNT] 2 DEGAUDED Deliver 60% of prescribed add at Fitting Cross
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Essilor ComputerTM - Benefits
Comfortable viewing at intermediate, near, and distance Wide clear intermediate area to see the entire screen (or other intermediate object) Some viewing at distance, to see across office No more head tipping
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Essilor ComputerTM - Fitting
Order just like normal progressive Dot center pupil Monocular Distance PDs 15 mm minimum Seg Ht 30 mm minimum B measurement Rx Range: to +7.00D cyl to -4.00
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Essilor ComputerTM - Uses
Besides computer viewing: Any Intermediate / near activity Sewing Carpentry Auto repair Cooking Optometry Painting Scrapbooking
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Essilor ComputerTM – Patient Wearing Trial
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EC Lens – Patient Preference
Wearers satisfied with current vision at computer PAL: n =33 1) Source: Essilor International – EC Lens Wearing Trial - October ‘05 (89 subjects ages 40+) UK, France
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NOT satisfied with current vision: n = 30
EC Lens – Patient Preference Wearers not satisfied with current vision at computer NOT satisfied with current vision: n = 30 1) Source: Essilor International – EC Lens Wearing Trial - October ‘05 (89 subjects ages 40+) UK, France
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Questions? Jon Torrey 503-781-8460 jtorrey@essilorusa.com
Thank You! Questions? Jon Torrey
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