We all know what pantoscopic tilt is. What do you call the tilt when the bottom of the lens is tilted outward from the face relative to the top of the lens?
retroscoptic ?
Retroscopic is correct. Retroscopic is also very wrong.
Ahh...I knew it was too easy.
WhyOriginally Posted by chip anderson
Because optically it does the exact opposite of what is needed by the patient (unless it's SV and he works in a country too small to have radar as an airplane spotter). If the patient has high forward cheekbones. You need another frame. Selling huge frames to negros (or PC misnomer of the moment) and american indians ( or PC misnomer of the moment) is wrong.
Chip
only wondered because my vision is best when there is no panto, or perhaps a tiny amount of retro ... perhaps I have very large ears :D
Perhaps you're cylinder correction needs tweeking.
Chip is correct for a couple of reasons. For starters, the wearer's lines of sight are almost inevitably above the datum (180) line of the frame, which is where the optical centers are generally located. This would necessitate some pantoscopic tilt in order to maintain proper optical performance (Martin's rule: 2 deg of tilt for every 1 mm the OC is located below the line of sight). Secondly, for most people, the bony orbit of the eye socket also has some vertical "pantoscopic" tilt to it, so having the frame follow this plane looks better cosmetically and also ensures the widest field of view through the lenses.
Darryl J. Meister, ABOM
So for SV if incorrect pantoscopic tilt provides best vision then the chances are that the OCs are not lined up correctly!
But surely there are some patients whose ears are slightly higher than usual (poor souls) and this might generate too much pantoscopic tilt ... the frame then could be adjusted so that the arms are perhaps at right angles to the lenses (no panto/no retro) ... and in the as worn position there might then be the correct amount of pantoscopic tilt.
Perhaps also a poorly fitted/poorly designed lens might contain a certain amount of oblique astigmatism that can be corrected when the panto goes retro
... and no, I'm not looking for advice about my own lenses ;)
Pantoscopic tilt in this context refers to the as-worn position.and in the as worn position there might then be the correct amount of pantoscopic tilt.
Darryl J. Meister, ABOM
You can tell that I'm not in the trade :hammer:
Hello, I was just lurking to try to find out more about glasses in general. Is this the tilt that brings the lenses closer to the cheek? If so my optician didn't bend the frames at all when he measured my eyes before ordering my progressive lenses. Is this routinely done when getting the measurements for new lenses? Or do they wait until after the glasses are made to do this? How does one know if a patient needs this tilt? I notice when I hold them and look from the side my current pair lean in and are not just straight up and down. I honestly do not remember what my old eye doctor did regarding that tilt.
By the way lest you think I'm trying to make a statement with my silly username it wasn't my idea! My sister was visiting and I asked her for a suggestion. My real name is Claire.
Spex: Mo' tilt mak u see bedda. U needs to toin yos til you can see over the top.Troll on
Chip
Fantastic username :)
I started to post here and realized it was the wrong thread. Sorry.
Last edited by GoodAsGold; 03-27-2006 at 12:17 AM.
Those would be great issues to bring up with YOUR optician ... let us know what he/she said ... :idea:
or not ... ;)
Thank you. Well he already sent my frames off to the lab, so I'll just hope that when they arrive he'll adjust them accordingly. I didn't even think about him tweaking the frames at the time of measurement. It was after I read it here that I realized that this tilt might be important at the time of fitting. Or not. So i thought I would ask you all what is the norm. I will also bring it up to him if he doesn't feel the frames need to be tilted toward my face. Perhaps he didn't think they did. He is new to me so I'm not as familiar with the way he does things yet. I believe he has been an optician for close to 20 years so i trust that he knows his business. Just wanted to see what everyone else usally does.
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