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Medical Forum / General / Vision / February 2008Progressive Lens Choices
I'd like to solicit advice about choosing progressive lenses for two pairs of eyeglasses, devoted respectively to generalized and occupational uses. I am 51 years old, with no history of eye diseases or surgeries. My primary generalized needs include driving and shopping. My primary occupational use is at a computer, with a large monitor about 30" from my eyes. I also play the piano, with the music stand and keyboard each about 20" from my eyes. I would add that the frames I'm considering (Silhouette 7481) offer generous areas above and below the pupils (Eye=47, Bridge=20, Vert=35). My current prescription is (Eye, Sph, Cyl, Axis, Add): OD -3.75 +2.75 x175 +2.00 OS -4.00 +1.50 x155 +2.00 I used Varilux Comfort lenses 3-5 years ago, with a similar distance prescription but a reading correction of only +1.00; I found the peripheral image blur fairly annoying. Lately I've been using single- vision lenses, sliding the frames down my nose for monitor viewing and looking over them for reading. I can see very well in these ways, but I've grown weary of the antics! Some specific issues that concern me: 1. Would I benefit substantially from the newer, individually designed progressive lenses that use free-form technology? On what basis might I choose between, say, the Hoya iD, Shamir Autograph, Zeiss Individual, or other models? Are there desirable alternatives at lower technology levels and prices? 2. Would I fare better in occupational use with an "office" type lens or with a regular progressive lens suitably adjusted (e.g., by moving some of the "Add" power into the "Distance" prescription)? Many thanks for your time and effort in reading this. David >I'd like to solicit advice about choosing progressive lenses for two >pairs of eyeglasses, devoted respectively to generalized and [quoted text clipped - 11 lines] >OD -3.75 +2.75 x175 +2.00 >OS -4.00 +1.50 x155 +2.00 It's probably safe to ignore the VI (vertical imbalance) with this type of Rx. However, if you wear multifocals, and you experience fatigue after a long stretch of close work, VI might be the culprit. >I used Varilux Comfort lenses 3-5 years ago, with a similar distance >prescription but a reading correction of only +1.00; I found the >peripheral image blur fairly annoying. Lately I've been using single- >vision lenses, sliding the frames down my nose for monitor viewing and >looking over them for reading. I can see very well in these ways, but >I've grown weary of the antics! It's time to specialize. (It's a different kind of antics.) >Some specific issues that concern me: > >1. Would I benefit substantially from the newer, individually designed >progressive lenses that use free-form technology? In general, and to varying degrees, yes. They won't feel like SV lenses though, and most folks don't experience a "considerable" improvement in acuity, FOV, and/or sense of refinement. That said, the difference will probably be much smaller than the difference between an accurately positioned lens and one that's poorly positioned. In other words, better quality lenses do not make up for bad opticianry. >On what basis might >I choose between, say, the Hoya iD, Shamir Autograph, Zeiss >Individual, or other models? Depends on the material choice, service, and the type of aberrations and distortion that needs to be minimized. However, looking at your situation; ie, changing from SV to a +2.00 Add PAL (progressive addition lens), I'd probably give the nod to the Hoya lens due to how well it reduces skew distortion, amongst other factors. The less expensive iD Lifestyle would be very close in performance, and comes in Trivex. Both come in two corridor lengths- the longer one (14mm) will have the best distance vision, and will still be ok for close tasks. >Are there desirable alternatives at >lower technology levels and prices? Any premium (multi-design, fully aspheric, numerous base curves, good binocular vision, etc.) PAL that has a generous distance zone would be ok. I probably wouldn't use a short corridor design for your situation, especially if you get multiple pairs. >2. Would I fare better in occupational use with an "office" type lens >or with a regular progressive lens suitably adjusted (e.g., by moving >some of the "Add" power into the "Distance" prescription)? IMO the latter. You still might need an additional pair of single vision for music- use a +1.50 or +1.75 for the Add, or if you need distance capability, then a high set ST35 (a wider than normal lined bifocal). However, you might find the computer glasses adequate for the sheet music. Make sure that the optometrist or optician shows you the quality of vision at both 20" and 30", using a variety of power combinations. >Many thanks for your time and effort in reading this. > >David Hope this helps, Robert Martellaro ~~~~~~~~~~~~~~~~~~ Optician/Owner Roberts Optical Wauwatosa Wi. ~~~~~~~~~~~~~~~~~~ "Science is a way of trying not to fool yourself." - Richard Feynman >It's probably safe to ignore the VI (vertical imbalance) with this type of Rx. >However, if you wear multifocals, and you experience fatigue after a long >stretch of close work, VI might be the culprit. Could VI be one of those things taken into account by the computer programs that calculate "individualized" lens surfaces? >In other words, better quality lenses do not make up for bad opticianry. If I lived within an hour of Wauwatosa, I'd beat a path to your shop. I do know of a "Guild" optician in my area. Does that designation count for something extra these days? >Depends on the material choice, service, and the type of aberrations and >distortion that needs to be minimized. However, looking at your situation; ie, [quoted text clipped - 4 lines] >one (14mm) will have the best distance vision, and will still be ok for close >tasks. I checked out Hoya's web-posted information on the iD Lifestyle, and it looks like an excellent choice on multiple criteria: design, materials, coatings. (It seems, however, that the longer corrider version is 18mm vs. the 14mm you cited.) I also received a reasonable price quote from the aforementioned Guild optician, which would put a second pair of the same lenses adjusted for office use well within range (pun not intended). I was impressed by Hoya's (realistic?) illustration of reduced swim effect on stairs. I'm surprised they don't tout it as a safety issue. But I wonder if anything in particular is attributable to the front-back split of the reading correction. Couldn't a ray-tracing program compute a back-only surface with identical performance? >You still might need an additional pair of single vision for music- use a +1.50 >or +1.75 for the Add, or if you need distance capability, then a high set ST35 >(a wider than normal lined bifocal). However, you might find the computer >glasses adequate for the sheet music. Make sure that the optometrist or optician >shows you the quality of vision at both 20" and 30", using a variety of power >combinations. I've been thinking about some of the peculiarities of the piano application. When marking music, it helps to see clearly at 12" inches. When reading music, it helps to see clearly at 20" for an upright, 30" for a grand. When positioning fingers on the keyboard, freedom from spatial distortion matters, so playing without refraction might be best. When playing in an ensemble, seeing other people's facial expressions at 6 to 12 feet can be important. Perhaps no single design can meet all these requirements optimally at once? >Hope this helps, >Robert Martellaro It does. I've leared a lot from your posts, here and on OptiBoard. >"Science is a way of trying not to fool yourself." >- Richard Feynman Sometimes the effort is actually made in earnest. /David >>It's probably safe to ignore the VI (vertical imbalance) with this type of Rx. >>However, if you wear multifocals, and you experience fatigue after a long >>stretch of close work, VI might be the culprit. > >Could VI be one of those things taken into account by the computer >programs that calculate "individualized" lens surfaces? Hopefully soon. >>In other words, better quality lenses do not make up for bad opticianry. > >If I lived within an hour of Wauwatosa, I'd beat a path to your shop. >I do know of a "Guild" optician in my area. Does that designation >count for something extra these days? It shouldn't rule anyone in or out. It doesn't sound like you'll have any problems finding out who's competent. >>Depends on the material choice, service, and the type of aberrations and >>distortion that needs to be minimized. However, looking at your situation; ie, [quoted text clipped - 9 lines] >materials, coatings. (It seems, however, that the longer corrider >version is 18mm vs. the 14mm you cited.) Hoya is describing the minimum fitting height- the lens with an 18mm minimum height has a 14mm corridor, the 14mm minimum height has a 11mm corridor. Regardless, you'll probably do better with the former. >I also received a reasonable >price quote from the aforementioned Guild optician, which would put a >second pair of the same lenses adjusted for office use well within >range (pun not intended). You might not need the very best lens for the computer glasses- the reduced minus and Add power might make a less expensive lens design more than adequate. However, if the frequency of use is high, the increase in visual refinement with a more advanced design would probably be worth the expense, pocketbook willing. >I was impressed by Hoya's (realistic?) illustration of reduced swim >effect on stairs. I'm surprised they don't tout it as a safety >issue. But I wonder if anything in particular is attributable to the >front-back split of the reading correction. Couldn't a ray-tracing >program compute a back-only surface with identical performance? I'm told that what can be done on two surfaces can also be done on one surface, at least in regards to power and astigmatic error, and maybe unwanted surface astigmatism. However, Hoya is not just splitting the Add power on both surfaces, they're combining two plano cylinders on the front and back surface that sums the cylinder power to equal the Add power. This is said to reduce skew distortion, to a degree that can't be done working only one surface. >>You still might need an additional pair of single vision for music- use a +1.50 >>or +1.75 for the Add, or if you need distance capability, then a high set ST35 [quoted text clipped - 10 lines] >might be best. When playing in an ensemble, seeing other people's >facial expressions at 6 to 12 feet can be important. Consider an upside down half-glass reader. I used to get these from the now defunct Franel Optical. Great for myopes- set the focal length as needed and look underneath the frame for the real short distances. >Perhaps no single design can meet all these requirements optimally at once? Usually not, especially for advanced presbyopes. >>Hope this helps, >>Robert Martellaro > >It does. I've leared a lot from your posts, here and on OptiBoard. That's good to hear. I want consumers to have more knowledge, asking tough questions, making it easier for you to find competent opticians, especially in states where opticianry is not regulated. Robert Martellaro ~~~~~~~~~~~~~~~~~~ Optician/Owner Roberts Optical Wauwatosa Wi. ~~~~~~~~~~~~~~~~~~ "Science is a way of trying not to fool yourself." - Richard Feynman |
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