There are a couple of reasons he might do this. Let's address them one at a time:
1) Assuming he wrote it with optical quality in mind, it must be stated that polycarbonate's optical qualities (measured as something called an ABBE value) are not quite as good as some other choices. The difference, for most people, is theoretical...but there are some who are super-sensitive to the aberrations created by polycarbonate vs other materials. Maybe you're one of them...have you had bad experiences with poly before? 2) Assuming he wrote it with your vanity in mind, most people prefer their lenses to be as light and invisible as possible. High index plastics can do that, regardless of your prescription. It's a matter of cost effectiveness, rather than materials science. 3) Assuming he wrote it as a money grubbing jackass, it could just be a way to extort extra money out of you. Your prescription is not very severe, and is in the range that is well served by poly lenses...by removing that option you are forced to use either excellent (but thicker and heavier) CR39 plastic lenses that you may not be happy with...or uber-expensive high index lenses, which he probably makes a fortune by selling. (It's sad that option 3 is believable, isn't it?) Were I in your position, I would confront him with the following question: Is there a specific reason why my prescription specifies to not use polycarbonate? Make him give you a comprehensible answer...not a bunch of technical mumbo-jumbo. And, finally, here's the standard link to the online thickness calculator. You'll notice that the difference in lens thickness, at your level of correction, is practically negligible. http://www.opticampus.com/tools/thickness.php -- Chuck Knight On Sat, Jun 20, 2009 at 5:32 PM, milodesc<[email protected]> wrote: > > Hi all - > > I am looking to get some old frames reglazed. > > I'm looking at 39dollarglasses but I'm not sure if I should get their > "Polycarbonate (thin & ultra-light) Lenses" [http://www. > 39dollarglasses.com/cgi-bin/store/info_pop/lenses.html#OPT1] or their > "Seiko® 1.67 Super-High Index Lenses" [http://www.39dollarglasses.com/ > cgi-bin/store/info_pop/lenses.html#OPT2]. > > My prescription [http://farm4.static.flickr.com/ > 3637/3644480439_8ba73fd696_b.jpg]: > OD: Sphere = -2.25, Cyl = -0.5, Axis = 085 > OS: Sphere = -3.25, Cyl = "Sph", Axis = [blank] > PD = 60 > > Since my prescription isn't very severe and I'll be using plastic, > rimmed frames, I thought the "Polycarbonate (thin & ultra-light) > Lenses" option would be the best choice. However, the "Comments" > section of my prescription reads: "No Polycarbonate". > > Any idea why the Dr. would say "No Polycarbonate"? > > Any help would be much appreciated. Thanks! > > > > --~--~---------~--~----~------------~-------~--~----~ Check us out at the oft-updated http://glassyeyes.blogspot.com! You received this message because you are subscribed to the Google Groups "GlassyEyes" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/glassyeyes?hl=en -~----------~----~----~----~------~----~------~--~---
