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Medical Forum / General / Vision / May 2005Silhouette and trivex lenses - question about optics vs. normal lenses
I just picked up some Silhouette rimless glasses with trivex lenses and I am having a hard time adjusting to the optics. I thought the drill mounts might take some getting used to but it's been the poor optics that have confounded me. My question is, should I be able to notice a difference between regular plastic lenes and the trivex lenses in a drill mount? The lens shape isn't all that much different (although it is slightly wider and slightly less "tall"). My vision with the regular lenses (in normal frames) was very good. My script is: -3.25 + 1.25 x 10 -3.00 + 1.00 x 178 It almost seems like they are making me "cross-eyed" but I also notice the bending of lines (upward when looking down through the bottoms) and the floor seems much closer to me...sort of magnified. I'm going back to the Dr. but thought I would give these a week or so, so I could try to observe what might be off. Thanks for any help. There will be some chromatic aberration that may take some adjustment, but it shouldn't take more than a few hours to adapt. If it continues, I'd suspect the P.D. being off, or some prism, or the Rx itself. Have it checked out. Trivex are certainly optically better than polycarb, the other drill mount option. w.stacy, o.d. > I just picked up some Silhouette rimless glasses with trivex lenses and > I am having a hard time adjusting to the optics. I thought the drill [quoted text clipped - 15 lines] > > Thanks for any help. >I just picked up some Silhouette rimless glasses with trivex lenses and > I am having a hard time adjusting to the optics. I thought the drill [quoted text clipped - 15 lines] > > Thanks for any help. Trivex lenses have very good optics compared to other mid or high index lenses and your Rx is not that strong to begin with (which can exacerbate optical problems with some lenses). So I do not think it is the lens material that is the problem. The lenses may not be placed correctly in your frame for where your frame sits on your face, or the Rx could be off, or the lens could be made incorrectly. It would also help to compare your old and new Rx to see what the difference is. I actually have the same rx in the normal (sola?) lens so I can do a pretty good A/B comparison. It's very odd when I do that and it appears from the replies so far I shouldn't expect to see that kind of response just because of trivex. >I actually have the same rx in the normal (sola?) lens so I can do a > pretty good A/B comparison. It's very odd when I do that and it appears > from the replies so far I shouldn't expect to see that kind of response > just because of trivex. Sola is a manufacturer that uses many different lens materials, just like Hoya, Younger, Essilor, Rodenstock, etc. I assume your old lenses are regular plastic 1.50 (aka CR-39 or hard resin). If the Rx is the same, then you should not see that much difference in a single vision lens. So the solution is to have a 3rd party do careful lensometry on both pair, including marking the optical centers and comparing the distances between them (p.d.s). Post the results here. They might also want to check the base curves. Oh and one other thought re base curves, do you know if you got aspheric or spheric Trivex? The come both ways. If they gave you aspheric, that could be the problem, or it could be the solution. w.stacy, o.d. > I actually have the same rx in the normal (sola?) lens so I can do a > pretty good A/B comparison. It's very odd when I do that and it appears > from the replies so far I shouldn't expect to see that kind of response > just because of trivex. >I just picked up some Silhouette rimless glasses with trivex lenses and >I am having a hard time adjusting to the optics. I thought the drill [quoted text clipped - 15 lines] > >Thanks for any help. Have your optician do the following: Adjust the frame so it sits as close as possible to the eyes, and increase the lens tilt, which looks like this from the side / . The perspective looking down will be much improved. If the top of the lens is too noticeable after this adjustment then use a larger lens or compromise on how close the lenses rest in front of the eyes (moving the lenses closer also lowers the lens position). Confirm that the vertical optical centers are lowered 1mm for every two degrees of lens tilt. For example the tilt is ten degrees then the vertical OCs should be 5mm below the pupil center. A simple way to verify the correct position is to look straight ahead and tilt your head back until the lenses are perpendicular to the floor. A horizontal ink line drawn through the optical centers should bisect the pupils. Check the monocular PDs (distance from the bridge center line to the right and left pupil centers. The lens OC should be no more than 1mm from the horizontal pupil center. When the lenses are positioned properly the visual comfort will match the physical comfort of these extremely lightweight eyeglasses. Hope this helps Robert Martellaro ~~~~~~~~~~~~~~~~~~ Optician/Owner Roberts Optical robopt@execpc.com ~~~~~~~~~~~~~~~~~~ "An expert is a person who has made all the mistakes that can be made in a very narrow field." - Niels Bohr Thanks for all the input. My doc checked them and they found that the PDs were indeed incorrect. They've been sent back to the lab, etc. so hopefully they'll get it right this time. It was nice to know I wasn't just being a pain in the rear. I'm looking forward to getting these back as they truly are remarkable frames - very comfortable. |
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