I second Chuck's comment that the same glasses shop can and does use different suppliers and even different labs, this is quite possibly the situation.
Although it's possible, I don't necessarily agree with Paul that a lower index lens was used. It would be noticeable for the wearer in such a high hyperopic correction (not so much for high myopic), your son would notice a difference in magnification when viewing near objects. Have him do a test between both glasses - view an object in front of him (something with a sharp edge works best) about 6 feet away, keep his eyes on the object and turn his head side to side, to the farthest extreme of his peripheral vision. This will allow him to notice the aspheric 'shape' or design - the least amount of distortion he see's, the better design of the aspheric lens (generally). Now do the same test but this time tilt the head up and down until he looks over the glasses (the unapproving school teacher look). By moving the head up and down just slightly he will see how much magnification is in the lens. The difference will be slight between the different lenses, or maybe not at all. But if he notices a difference then the lenses that appears less magnified might have a higher index rating. Surfacing is when they machine or "sand down" (think woodworking) the additional thickness of the lens after it's cut for shape. All lenses that are +4.00 and above need this additional surfacing because nearly all lenses below a +4.00 are what they call 'stock lenses' - that is a lens that is already thinned at the edges that all they have to do is cut to shape. See the nice tutorial at the 'how stuff works' website: http://science.howstuffworks.com/lens7.htm The question now is what can you do about it? Well, probably nothing about the current lenses, as long as the prescription is correct, they technically have delivered the product you ordered. Unless you speak with the Lab directly, the sales people you deal with over email/phone likely know little about the surfacing procedures and would not be forthcoming even if they were. You could take advantage of the EyeBuyDirect 30% off sale on the GlassyEyes site and get him a pair of 1.74 index lenses for only $78. That's 30-40% less than almost anywhere else. It's the highest index commonly available and you could always rest easy that you've done everything you could to reduce his trauma at school. Otherwise, try spending a few months with a qualified optician to fit contact lenses. I've spent years trying to find a workable solution without much success (not many manufacturers produce lenses in high plus corrections), but he might have better luck. On Apr 16, 9:28 pm, BJ <[email protected]> wrote: > In my case the lenses are actually twice the same quality from the > same manufacturer. > > I had heard this term 'surfacing' before, but am not quite sure what > it means. So it is actually a way of making thinner lenses? > > It could be an explanation. But I find that strange, why would the > same company do it in some cases, and not in other cases? > > BertJan --~--~---------~--~----~------------~-------~--~----~ Check us out at the oft-updated http://www.glassyeyes.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 -~----------~----~----~----~------~----~------~--~---
