GCO- Progressive addition lenses (PALs) 2021 PDF

Progressive Addition Lenses http://www.antiquespectacles.com/topics/franklin/franklin.htm Adam Gordon, OD, MPH, FAAO 1 2 Introduction ▪State-of-the-art ophthalmic lens technology for presbyopia ▪Over 50 manufacturers...

Progressive Addition Lenses http://www.antiquespectacles.com/topics/franklin/franklin.htm Adam Gordon, OD, MPH, FAAO 1 2 Introduction ▪State-of-the-art ophthalmic lens technology for presbyopia ▪Over 50 manufacturers with over 300 designs! ▪Most frequently prescribed option by OD’s ▪US market since early 1970’s 3 Course Overview 1. Design principles- general purpose PALs 2. Short-corridor PALs 3. Occupational progressive lenses (OPLs) 4. Fitting and dispensing 5. Digitally-surfaced (free-form) lenses 4 What are PALs? Lenses that provide distance, intermediate, and near vision without lines or segments 5 Gradually Increasing Add Power ▪ Continuous ↑ in add power from top to bottom of lens ▪ Add power varies from 0 in top to full add in bottom ▪ Progressive zone: channel or corridor of changing power 6 PAL Benefits- Better Vision ▪ Clear vision at all distances ▪ Simulates pre-presbyopic vision ▪ Lens “adapts to the environment” 7 PAL Benefits- Better Cosmesis ▪ Looks like a regular lens ▪ No lines or interrupted fields ▪ Doesn’t broadcast “middle age” to the world! ▪ No image jump 8 How Do They Work? Distance Zone Intermediate Zone Reading Zone Unwanted Astigmatism 9 How Do They Work? ▪Complex aspheric design molded on front surface of semi-finished blank ▪Back surface finished by lab for sphere & cylinder power ▪Progressive corridor begins 4 mm below pupil ▪Smooth ↑ in add throughout corridor until maximum is reached 10 How are PALs designed? Sophisticated engineering & vision science ▪ Iterative process with optimization software ▪ Merit Function- evaluates multiple characteristics at each point on lens 11 Unwanted Astigmatism (aberration) Produced by all PALs ▪Side-effect of complex aspheric surfaces ▪Non-rotationally symmetric surfaces ▪Surrounds progressive corridor and near zone ▪Produces “blur” and “swim” in periphery 12 Astigmatism 101 We know about astigmatism, right? ▪ Which is better, 1 or 2? ▪ Football vs. basketball ▪ Line images, COLC 13  Astigmatism 101, cont. Marginal (radial) astigmatism ▪Oblique incidence of off-axis object points ▪Same as lens tilt ▪Important spectacle aberration ▪Minimized by BC selection (“corrected curve lenses”) 14  Astigmatism 101, cont. Unwanted astigmatism with PALs is different ▪ Refers to lens aberration outside the normal viewing zones Unavoidable result of complex, non- rotationally symmetric aspheric surfaces 15 Unwanted astigmatism increases: 1. As add power ↑ 2. As the width of the near & intermediate zones ↑ 3. As the progressive corridor becomes shorter “Optical Facts of Life” Manufacturers balance the size of the zones and the astigmatism 16 Add power & astigmatism Unwanted astigmatism is proportional to add power 17 Clinical Pearl Be careful and educate the patient if: ▪The add power ↑ ▪Changing to a short-corridor PAL for the first time ▪Both of the above 18  Drawbacks of PALs ▪Narrower near zone than BF ▪Narrower intermediate zone than TF ▪Requires more lateral head-turning ▪Must lower eyes further into lens for near vision ▪Peripheral blur or “swim” ▪Distortion of lines 19 What Do Patients Prefer? ▪In numerous clinical trials worldwide, 80-90% of subjects prefer PALs over BF and TF ▪No differences by gender, refractive error, add power, or previous Rx ▪Anisometropes & mixed astigmats were lower (61%, 67%), but still chose PALs. 20 PALs vs. Bifocals Intermediate blur or “gap” 1.50 D Amp Accom; +2.00 D add power 21 PALs vs. Bifocals Continuous, clear vision without a “gap” 22 Viewing Computer with Bifocals Bifocal #1: Lower chin, look through top of lens, and move further away from screen. ▪ Accommodation exerted Bifocal #2: Raise chin, look through bottom, and move closer to screen ▪ Accommodation fully relaxed 23 Viewing Computer with PALs ▪ Patient slowly raises chin until computer screen is in focus. ▪ Maintains more normal posture. ▪ Accommodation is fully supported for all working distances. Does not shift from one extreme to the other. 24  PAL Markings Temporal alignment circle and add power are permanent engravings Nasal alignment circle and manufacturer logo are permanent engravings 25 PAL Markings 1. Fitting cross 2. Engraved alignment circle 3. Prism reference point (PRP) 4. Engraved add power 5. Distance reference circle 6. Engraved alignment circle 8 7. Manufacturer’s symbol or logo 8. Near reference circle 26 Design Terminology ▪ Hard vs. soft designs ▪ Spherical vs. aspherical designs ▪ Mono- vs. multi-designs ▪ Symmetric vs. asymmetric designs 27 Power profile Rate of change in add power throughout the progressive corridor or “channel” ▪ Measured from distance reference point (DRP) to near reference point (NRP) ▪ Progressive corridor begins 4 mm below fitting cross ▪ Add power ↑ from 0 to prescribed add power ▪ Gives distance from pupil center to full add power (in mm) ▪ Shows how quickly the add power changes 28 Contour Plots Isospherical contour plot: spherical equivalent Isocylinder contour plot: most common 29 Contour plots are misleading! Same lens! ▪ Isosphere or spherical equivalent ▪Isocylinder or astigmatism 30 Contour plots: Same lens! Unwanted Spherical equivalent astigmatism in in diopters diopters 31 Hard vs. Soft Designs: 2 extremes 32 Hard vs. Soft Designs Hard Design ▪ Wider distance & near zones ▪ Faster rate of change ▪ Narrower, shorter corridor ▪ More concentrated zones of intense astigmatism ▪ Harsh transition Soft Design ▪ Narrower distance & near zones ▪ More gradual rate of change ▪ Wider, longer corridor ▪ Less concentrated, less intense astigmatism ▪ Gradual, softer transition 33  Spherical vs. Aspherical Refers to upper half of lens ▪ All PALs have aspheric surfaces ▪ Similar to hard (“spherical”) vs. soft (“aspherical”) ▪ Poor wording since all PALs are aspheric to some degree 34 Mono vs. Multi- Design Mono: same design for all add powers Multi: optimized design for each add power 35 Fitting & Dispensing PALs 36 Short Essilor Videos We’ll watch a few, but please watch on your own! ▪ Each video is brief; 1-3 minutes & somewhat entertaining… ▪ Good information/review https://info.icarelabs.com/varilux-resource-center#varilux_ecp_resources You are responsible for the following Varilux videos: 1. Measuring monocular PDs 2. Measuring fitting height 3. Re-create the fitting cross 4. Confirm measurement and prescription 37 Handy Reference Progressive Lens Identifier ▪Online resource & free pdf download ▪Gives minimum fitting heights, BC’s, & indexes ▪Manufacturer’s symbols ▪Lens templates https://epic.thevisioncouncil.org/ 38 Select Appropriate Frame ▪ Must have adequate B-size ▪ Most general purpose PALs: 18 mm fitting height ▪ Minimize horizontal decentration 39 Adjust Frame First! ▪ Minimum VD ▪ 8-12° pantoscopic tilt ▪ Nose pad adjustment ▪ Temple length & bend 40 Fitting PALs: Monocular PD Corneal reflection pupilometer (CRP) ▪Monocular distance PD’s ▪Eye level with patient ▪Have patient hold CRP steady 41 Fitting PALs: Dot Pupil Centers ▪ Must be at eye level ▪ Patient fixates at distance ▪ Support hand on patient’s face ▪ Double-check 42 Dotting Center of Pupil 43 Measuring Fitting Height ▪ Draw horizontal line through pupil marks ▪ Much easier to check positioning 44 Measuring Fitting Height Double-check fitting height measurements ▪“Measure twice, cut once” Minimum fitting height must be appropriate for the frame size (B-size) 45 Dispensing to Patient ▪ Leave markings on lenses ▪ Adjust frame for proper fit & alignment ▪ If OK, remove markings 47 Dispensing to Patient ▪ Instruct in proper use ▪ Demonstrate head turning ▪ Demonstrate chin movement ▪ Let patient stand & walk around 48 Essilor PAL Fitting/Dispensing Guide ▪Free download ▪Handy, concise summary for all PALs ▪Great for training staff https://www.essilorusa.com/content/dam/essilor-redesign/product- resources/varilux/LVAR201326_Varilux_Fitting_N_Dispensing_Guide_LR.pdf 49 Digital PAL fitting methods Use video capture with image analysis to measure: ▪ Monocular PDs ▪ Fitting heights Digital methods also capture “position of wear” measurements: ▪ Vertex distance ▪ Pantoscopic tilt ▪ Frame wrap Additional measurements: ▪ Reading distance ▪ Dominant eye ▪ Head posture ▪ Frame size: A, B, DBL 50 Why use digital fitting devices? Standard methods (CRP, marking pupil by hand) are not precise enough for many patients ▪ High or complicated Rx ▪ Previous nonadapt to PALs New free-form PAL designs can be manufactured to 0.01 D precision ▪ Precise fitting measurements reflect “position of wear” ▪ Lens design can be optimized for anatomy & posture of patient ▪ Lens designs can minimize lens aberrations & improve image quality ▪ Future designs can minimize patient ocular higher order aberrations 51 Digital PAL fitting methods The Smart Centration system Otto, an iPad-based system, from ABS, Inc., Smart Mirror The Visioffice System from from VSP Optics Group Essilor of America 52 Digital PAL fitting methods 53 Short Corridor PALs 54 Short-Corridor PALs 55 Short-Corridor PALs ▪ For smaller frames with shorter B- sizes ▪ Fitting heights 14-16 mm ▪ AO Compact, Varilux Ellipse, Shamir Piccolo ▪ ↑ astigmatism (aberration) 56 Varilux Ellipse ▪14 mm fitting height ▪Rapid power change ▪Reaches 85% of add power at 9.5 mm 57 Varilux Ellipse ▪ Minimizes downward head tilt ▪ Expanded distance vision field 58  Occupational Progressive Lenses (OPLs) http://barterfirst.com/what-can-i-buy-with-barter-dollars/ 59 Occupational Progressive Lenses (OPLs) ▪ Task-specific lenses ▪ Designed for intermediate & near viewing tasks ▪ Computers https://newgradoptometry.com/are-you-prescribing- essilor-computer-lenses-for-your-presbyopes/ 60 Occupational Progressive Lenses (OPLs) Upper lens: low add (+0.50 - +0.75D) Middle of lens: intermediate add Lower lens: full add power ▪ Add power “degresses” from maximum add at bottom to minimum add at top ▪ Much wider intermediate and near vision zones 61 OPLs- Examples https://www.hoyavision.com/sg/discover-products/for-eye-care- professionals/occupational-lenses/hoyalux-workStyle/ https://www.shamirlens.com/products/shamir-lenses- products/item/29-shamir-computer-workspace https://www.zeiss.com/vision-care/us/for-eye-care- professionals/products/eyeglass-lenses/office-lens-portfolio-by-zeiss.html#benefits https://www.zennioptical.com/workspace-progressives 62 How do we Rx OPLs? ▪Same as a regular lens! ▪ Specify distance Rx and regular add power for 40 cm ▪ Specify brand of OPL ▪Lab fabricates lens to have full near power in bottom of lens ▪Lab uses total near power as reference, not distance Rx 63 Reference Article 64 OPLs- Sheedy study OPLs measured with Rotlex Class Plus lens analyzer Rx plano with +2.50 D add 65 OPLs- Sheedy study conclusions ▪ Large differences in designs ▪ Reflects intended use ▪ Main difference: amount of degression & distal range of vision ▪ ↑degression gives ↓corridor width due to ↑unwanted astigmatism 66 OPLs- Sheedy study conclusions Sheedy & Hardy Optometry 2005;76:432-441 67 OPLs- Shamir Office Lens 68 Shamir Office Lens 69 Shamir Office Lens Degression power +0.25 D add = 4 m = 13.20 ft +0.50 D add = 2 m = 6.60 ft 70 Free-Form (Digital) PALs 71 Free-Form Manufacturing ▪ Allows virtually any shape to be lathed on any surface! ▪ Progressive surface applied to front, back or both surfaces ▪ ↑ fields of view, ↓blur and curving of lines ▪Allows “customization” of PALs ▪Wavefront correction of HOA’s is possible 72 Traditional PAL Manufacturing ▪Manufacturer produces semi- finished blanks ▪Base curve & progressive design with add power is pre-molded on front surface ▪Optical lab grinds back surface for sphere & cylinder ▪Rigid lap tools used for grinding & polishing 73 Free-form Surfacing ▪ Sophisticated software and CNC lathes ▪ Can create any curve on either surface or both surfaces with high precision ▪ Lathe operates in 3-D, not 2-D 74 Free-Form PALs Back surface designs ▪ Seiko Proceed Internal ▪ Rodenstock ILT ▪ Shamir Autograph Dual-add design ▪ Definity (J&J, now Essilor) ▪ Varilux Physio 360 ▪ Hoyalux iD 75 Essilor Definity 76 Essilor Definity ▪ Less distortion than leading PALs 77 Definity Definity Single surface PAL DUAL ADDTM TM PAL 78 Essilor Definity “Ground view advantage” ▪ A 4th zone of decreasing add power below the near zone ▪ May provide better vision for walking, stairs, golf, etc. 79 Definity Short ▪Same design with short corridor ▪Minimum fitting height: 15 mm 80 HOYALUX iD Unique, dual surface PAL Horizontal power gradient on back surface ▪ ↑ field at all distances ▪ No swim effect ▪ ↓ image distortion in periphery 81 HOYALUX iD Vertical power changes on front surface ▪ ↓ eye rotation ▪ Fast compensation for accommodation ▪ Rapid interaction between near and far 82 HOYALUX iD Front & back surfaces balanced & integrated ▪ Stable image perception ▪ Even distribution of performance ▪ ↓ head movements 83 Varilux Physio Wavefront optimized PALs ▪ Physio- optimized front surface ▪ Physio 360- both surfaces optimized Free-form technology: 0.1 micron precison 84 Varilux Physio Front surface is optimized: ▪ Coma is minimized in distance zone ▪ Unwanted cyl axis shifted closer to 090° around progressive corridor ▪ Stabilized near zone has  height 85 Varilux Physio Distance vision: coma is minimized ↑ visual acuity, ↑ contrast 86 Varilux Physio Intermediate vision: axis of unwanted astigmatism surrounding corridor shifted closer to x090 ↑ image clarity and ↓ accommodative effort 87 Varilux Physio Near vision: ↑ height & area near zone 88 PAL Summary 1. PALs are the most prescribed spectacle lens design for presbyopia ▪ 80-90% of presbyopes prefer PALs to all other designs in clinical studies ▪ No visible lines/segments, continuous ↑ in add power 2. Unwanted astigmatism/aberration surrounds intermediate & near zones ▪ Peripheral blur, “swim” ▪ Design becomes “harder” with higher add powers & shorter corridor lengths 3. Fitting measurements: monocular distance PDs & fitting height from pupil center ▪ General purpose PAL: 18 mm minimum fitting height ▪ Short corridor PAL: 14-16 mm minimum fitting height 4. Alignment circles nasal & temporal on each lens allow mark up for measurement, using manufacturer template ▪ Fitting cross, optical center/PRP, distance reference circle, near reference circle 89 PAL Summary, cont. 5. Measure PAL powers the same way as bifocals ▪ Distance power with BVP ▪ Reverse glasses and measure add power with FVP (2 readings) 6. Patient education is critical for proper use & adaptation ▪ Turn head, raise chin, & lower eyes in lens 7. Occupational PALs (OPLs) are great for computer users ▪ Based on degression from total near power ▪ Very wide intermediate & near vision fields; minimal or no distance vision ▪ Many different designs available 8. Free-form (“digital”) lenses allow progressive channel to be placed on front, back, or both surfaces ▪ Can minimize lens aberrations, provide better image quality, & wider viewing fields 90 91