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Thread: Fitting heights in deep frames

  1. #1
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    Fitting heights in deep frames

    Most frames I sell have frame depths of 35-45mm. For frames of 35mm I usually have a fitting height of 22-23mm with 14mm corridors (center of pupil) or 19-22 with 10mm corridors (center pupil -2mm). I never go lower than 18-19mm.

    My question is: am I fitting too high? A 23mm height in a 35mm frame only leaves 12mm for distance which seems very limited. On the other hand some clients have complained that reading is difficult when fit lower than pupil center with 14mm corridors. I try to avoid short corridors unless for low adds, high myopia, very short vertex distance (11mm or less) or people who are used to them.

    I only lower the seg height to center pupil -1/2mm for tall people, truck/bus drivers and short corridors (10mm). Are there any other exceptions? What about large vertex distances (15-16mm)?

    I get very little returns but I have the feeling that a lot of people with complaints do not return. I also work in different locations so it's hard to obtain feedback from most of my clients. This is very frustrating because my fittings could be nothing more than adequate while I always do my best to aim for perfection.

    We only sell Hoya lenses (Summit CD/Pro, ID Lifestyle and Mystyle) which are all 4 drop and have corridor lengths of either 10 or 14mm.

    Any feedback would be greatly appreciated.

  2. #2
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    Quote Originally Posted by Airegin View Post
    Most frames I sell have frame depths of 35-45mm. For frames of 35mm I usually have a fitting height of 22-23mm with 14mm corridors (center of pupil) or 19-22 with 10mm corridors (center pupil -2mm). I never go lower than 18-19mm.

    My question is: am I fitting too high? A 23mm height in a 35mm frame only leaves 12mm for distance which seems very limited. On the other hand some clients have complained that reading is difficult when fit lower than pupil center with 14mm corridors. I try to avoid short corridors unless for low adds, high myopia, very short vertex distance (11mm or less) or people who are used to them.

    I only lower the seg height to center pupil -1/2mm for tall people, truck/bus drivers and short corridors (10mm). Are there any other exceptions? What about large vertex distances (15-16mm)?

    I get very little returns but I have the feeling that a lot of people with complaints do not return. I also work in different locations so it's hard to obtain feedback from most of my clients. This is very frustrating because my fittings could be nothing more than adequate while I always do my best to aim for perfection.

    We only sell Hoya lenses (Summit CD/Pro, ID Lifestyle and Mystyle) which are all 4 drop and have corridor lengths of either 10 or 14mm.

    Any feedback would be greatly appreciated.
    From my perspective, the total above the seg is not by itself all that significant (even with only 12 mm). What is more significant is the total height from pupil to the top of the there field of vision. They should not be able to see the top of the frame,without tilting their head down or looking up. If they can see the top if the frame while looking straight ahead, it needs to be adjusted prior to measuring the segment.

  3. #3
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    I think your measurements sound good (without actually seeing any of the fitting of course) in a sense that you are following the 2/3rds ruling. Frames will ideally sit with the pupil being placed between the top third and OC of the lens. This will make sure there is enough room for the full span of Rx in a progressive.

    What I differ on greatly, is that my office has great success with fitting low and using short corridors. I tend to fit at the bottom of the pupil (extra -1mm for people over 6' and anti-fatigue lenses) and go with minis. We also use Hoya lenses for the majority of our patients too.

    By no means does this mean I think you should change anything you are doing. I commend the strive for perfection, but I don't think you should disturb a process that is working for your patients.
    Have I told you today how much I hate poly?

  4. #4
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    Thanks for all the feedback. I'm always happy to do a re-do if I messed up but most people with complaints would see one of my co-workers who are less inclined to do so.

    I recently had a big complaint from a client who saw a ton of distortion. She had -2.00 cilinders. My co-worker had fit her with a short corridor Hoya Mystyle without measuring vertex distance and panto. Her previous lenses were ID Lifestyle with a long corridor. Client came back after just an hour. I measured everything again and vertex distance was a whopping 16mm (same as previous pair and unable to shorten it using the nose pads). I didn't hesitate to order a new pair with a long corridor because it was all messed up and impossible to get used to.

    A lot of my co-workers only fit short 10mm corridors and I was told to do the same. It seems to work out for a lot of clients but I feel that longer corridors can provide a better optical experience due to much less distortion and way better intermediate. I believe these lenses are superior but only with proper fitting height. There are of course exceptions so I always check the previous pair's corridor and ask about lifestyle.

    I don't see any reason to ever go with short corridors for hyperopes with 2.50 add though. Especially with bigger frames these days, which require seg heights of 22-28mm. The induced prism would make it hard to read and force the client to look deeper under the reading area where the add can reach up to 125%.
    Last edited by Airegin; 03-12-2018 at 01:51 PM.

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    With modern lenses I never ever "fit" anything other than center pupil. Do not think of it as "fitting" the progressive lens anymore like we used to with grinders. You are giving the software the height of the pupil in the frame. If the patient is complaining about something with their vision, change the corridor, change the design - it is by tailoring these values that we are "fitting" progressives these days. If you don't give the software proper measurements all of the calculations and geometry then surfaced will be off.

    It is a bad bad habit from older days. Believe me I spent time surfacing and edging plenty of AO compacts 2mm below center pupil, same as I Bumped the add up in an ovation to create a "short fit" lens. But this is not optimal, and competely not applicable with todays free form on the fly designs.

    With front side pals, there may still be room to do these old techniques.

  6. #6
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    I agree. I fit at the corneal reflex, which I use a penlight to find. And I always make sure nosepads are adjusted. I have the patient put them on, mark, remove and draw a short line at the dot. I have the patient put on again and recheck.

    I also use the dots to double check my PDs.

  7. #7
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    Remember that patient’s vision is from the viewing perspective and it is completely relative to their posture and head position. No matter what the B measurement is it should be relative to center pupil position in frame +/- variables as mentioned in previous posts. This is when you’re using a good modern design progressive lens. The old rule of thumb is +4mm from center of B for progressives and -3mm for flat tops, and if it comes out different double check.

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    Quote Originally Posted by Tallboy View Post
    With modern lenses I never ever "fit" anything other than center pupil. Do not think of it as "fitting" the progressive lens anymore like we used to with grinders. You are giving the software the height of the pupil in the frame. If the patient is complaining about something with their vision, change the corridor, change the design - it is by tailoring these values that we are "fitting" progressives these days. If you don't give the software proper measurements all of the calculations and geometry then surfaced will be off.

    It is a bad bad habit from older days. Believe me I spent time surfacing and edging plenty of AO compacts 2mm below center pupil, same as I Bumped the add up in an ovation to create a "short fit" lens. But this is not optimal, and competely not applicable with todays free form on the fly designs.

    With front side pals, there may still be room to do these old techniques.
    I agree with this for medium/long corridors. Center pupil on short corridors has been uncomfortable for my clients though. They have to lower their chins to clearly see the lower part of the TV for example. For short corridors I always take -1 or -2mm now.

    Also, I have 2 hyperope family members with 2.75 add (long corridor) who were much happier with their distance after adjusting their frames to center pupil -1mm. It wasn't enough of a complaint to return to their optician though. In both cases it was a matter of being able to slightly lean back while watching TV.
    Last edited by Airegin; 03-31-2018 at 04:01 PM.

  9. #9
    One eye sees, the other feels OptiBoard Silver Supporter
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    Quote Originally Posted by Airegin View Post
    I agree with this for medium/long corridors. Center pupil on short corridors has been uncomfortable for my clients though. They have to lower their chins to clearly see the lower part of the TV for example. For short corridors I always take -1 or -2mm now.
    Clearly, the solution is to use a medium length corridor that is exactly 1mm to 2mm longer, or ramps up the power 1mm to 2mm later.

    Also, I have 2 hyperope family members with 2.75 add (long corridor) who were much happier with their distance after adjusting their frames to center pupil -1mm. It wasn't enough of a complaint to return to their optician though. In both cases it was a matter of being able to slightly lean back while watching TV.
    No lean. No lean. You lean.

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