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Medical Forum / General / Vision / July 2006Selecting lenses
I would be grateful if anyone could offer some advice on selecting single-vision lenses for a drilled rimless frame. Prescription: SPH CYL AXIS PRISM BASE VIA R -2.25 -0.50 52.5 - - 6/6 L -2.00 - - 6/6 Add R +2.00 L +2.00 PD is 68 mm I have worn Zeiss CR-39 lenses (no other details, I'm afraid) to a very slightly different former prescripton for many years with complete comfort. A new optician (I moved) tested me and ordered me some 1.6 index lenses from Shamir for some new rimless frames (Lindberg Spirit) and I have been getting used to them for three weeks. The new prescription (above) is fine on-axis. I can tolerate the much increased off-axis chromatic distortion. However the off-axis barrel distortion is too much. I no longer feel nausea, but after three weeks I still feel far too uncomfortable in confined spaces such as the aisles at the supermarket. I suspect it will not get much better with more time. The old Zeiss lenses showed very little of either distortion. But the new frames do need a 1.6 (or greater) index lens so CR-39 is apparently out. Is there some specific lens product I can ask for which will minimize the barrel distortion in a 1.6 index lens? I know some barrel distortion off-axis is normal but does it always get so much worse with 1.6 index lens material? I took advice from an independent optician and he suggested Hoya 1.6 Eyas. He said (if I understand correctly) that although the Eyas lens geometry did not specifically deal with barrel distortion he thought it would at least minimize it to the point of being no worse than the old Zeiss lenses. Does this sound right? I also understand the Hoya 1.6 Eyas has a good ABBE value so it will minimize the off-axis chromatic aberration (even if this is not a big issue for me). Any advice will be received gratefully. My priority is the performance of the lens, coming well above aesthetics.  SignatureJohn Phillips >I would be grateful if anyone could offer some advice on selecting >single-vision lenses for a drilled rimless frame. [quoted text clipped - 31 lines] >Is there some specific lens product I can ask for which will minimize >the barrel distortion in a 1.6 index lens? For a drilled rimless frame, a lens made out of TRIVEX is the material of choice in 07/2006. I would try Hoya's Summit ECP progressive in TRIVEX. The distortion in your 1.6 lenses may be due to the material or the lens design. It is hard to tell, but that is what I would recommend. [snip] >>I would be grateful if anyone could offer some advice on selecting >>single-vision lenses for a drilled rimless frame. [quoted text clipped - 24 lines] > in your 1.6 lenses may be due to the material or the lens design. It > is hard to tell, but that is what I would recommend. Thanks. I will push back and see if my optician will relent on the 1.6 index material and give me TRIVEX (1.53 I think). However just to be clear I am not after progressive lenses - just single vision for distance (sorry for the confusion - I just reproduced the entire prescription card and I guess the "Add" bit is not relevant to single vision lenses). SignatureJohn Phillips > Thanks. I will push back and see if my optician will relent on the 1.6 > index material and give me TRIVEX (1.53 I think). [quoted text clipped - 3 lines] > entire prescription card and I guess the "Add" bit is not relevant to > single vision lenses). Another good mid-index lens in Sola Spectralite 1.54, or if you need a 1.6 lens then Sola Finalite. If you want Trivex, both Hoya and Younger optical have SV lenses in this material. [snip] >> For a drilled rimless frame, a lens made out of TRIVEX is the material >> of choice in 07/2006. [snip] >Thanks. I will push back and see if my optician will relent on the 1.6 >index material and give me TRIVEX (1.53 I think). I would get the Trilogy or Phoenix Aspheric TRIVEX SV lens and recommend they try and match the front curves (as much as possible) of your old Zeiss CR-39 lenses. BTW, besides having slightly better optics than 1.6, TRIVEX is much stronger and less likely to break in a rimless design. >I would be grateful if anyone could offer some advice on selecting > single-vision lenses for a drilled rimless frame. [quoted text clipped - 47 lines] > Any advice will be received gratefully. My priority is the performance > of the lens, coming well above aesthetics. Your request say single-vision lenses, but your Rx includes an add power for bi-focals or progressives. Do want lenses only for the distance vision, or do you want progressives? >>I would be grateful if anyone could offer some advice on selecting >> single-vision lenses for a drilled rimless frame. [quoted text clipped - 12 lines] > bi-focals or progressives. Do want lenses only for the distance vision, or > do you want progressives? Sorry for the confusion. I just reproduced everything that was written on the prescription card. I definitely want single-vision lenses for distance vision so I suppose the "Add" informtion is irrelevant. SignatureJohn Phillips >I would be grateful if anyone could offer some advice on selecting >single-vision lenses for a drilled rimless frame. [quoted text clipped - 25 lines] >confined spaces such as the aisles at the supermarket. I suspect it >will not get much better with more time. Blur, color, or both? Chroma should be imperceptible at this power. There may be other problems that need correcting e.g. waves, warpage, incorrect lens positioning. >The old Zeiss lenses showed very little of either distortion. But the new >frames do need a 1.6 (or greater) index lens so CR-39 is apparently out. > >Is there some specific lens product I can ask for which will minimize >the barrel distortion in a 1.6 index lens? Nope. Moving the lenses closer to the eyes will help. Contact lenses would help the most. >I know some barrel distortion off-axis is normal but does it always get >so much worse with 1.6 index lens material? It's not the lens material, it's the lens positioning. >I took advice from an independent optician and he suggested Hoya 1.6 Eyas. >He said (if I understand correctly) that although the Eyas lens geometry >did not specifically deal with barrel distortion he thought it would >at least minimize it to the point of being no worse than the old Zeiss >lenses. Does this sound right? Nope. >I also understand the Hoya 1.6 Eyas has a good ABBE value so it will >minimize the off-axis chromatic aberration (even if this is not a big >issue for me). > >Any advice will be received gratefully. My priority is the performance >of the lens, coming well above aesthetics. Your optician might have some success in minimizing the awareness of this distortion (barrel) with your existing glasses by adjusting the panto (vertical tilt), the dihedral angle/facial wrap (horizontal tilt), and by reducing the vertex distance (moving the lens closer to the eyes). Hope this helps, Robert Martellaro ~~~~~~~~~~~~~~~~~~ Optician/Owner Roberts Optical ~~~~~~~~~~~~~~~~~~ "If a million people believe a foolish thing, it is still a foolish thing." - Anatole France >> SPH CYL AXIS PRISM BASE VIA >> R -2.25 -0.50 52.5 - - 6/6 [quoted text clipped - 18 lines] >> > Blur, color, or both? No colour problems now unless I deliberately look, when it is quite visible. However, I seem to have got used to it. In static situations I can focus now on objects in my peripheral vision (it was a problem initially but I seem to have adapted). Nevertheless in confined static situations (e.g. an elevator/lift) the horizontal displacement at the top & bottom of vertical lines is an extimated 5% of the vertical distance, which makes me feel uncomfortable. And as I walk down a supermarket aisle looking ahead I see both peripheral blur and the horizontal displacement at the top/bottom of vertical structures. That combination feels very uncomfortable still after three weeks. > Chroma should be imperceptible at this power. My prescription seems rather mild in the grand scheme of things so the aberrations seem rather surprising to me. They seemed also to be rather unusual to the independent optician I consulted. He told me he was wearing -11 Hoya 1.6 Eyas lenses and these were no problem at all to him. That's why he suggested those lenses. > There may be > other problems that need correcting e.g. waves, warpage, incorrect lens > positioning. OK. Thanks for that. I don't specifically understand the terms waves and warpage in this context but it's something I will pursue with my optician. >> Is there some specific lens product I can ask for which will minimize >> the barrel distortion in a 1.6 index lens? [quoted text clipped - 6 lines] > > It's not the lens material, it's the lens positioning. OK That's something I will pursue. >> I took advice from an independent optician and he suggested Hoya 1.6 Eyas. >> He said (if I understand correctly) that although the Eyas lens geometry [quoted text clipped - 17 lines] > > Hope this helps, Many thanks to you and to all others who have offered suggestions and points to examine. I will pursue these with my optician. SignatureJohn Phillips > No colour problems now unless I deliberately look, when it is quite > visible. However, I seem to have got used to it. [quoted text clipped - 9 lines] > vertical structures. That combination feels very uncomfortable still > after three weeks. Find out if you got polycarb. If so, take them back and get one of the other lenses recommended in this thread. I promise that you will see the difference. |
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