Using Wrap Calculators

[Bob Price]

Has anyone had success with compensating Rx's with a wrap calculator and satisfying the patient? If so, what methods were used to figure for wrap and tilt? Which calculator was used?

Thanks.

[HarryChiling]

I have had success, used my own, and basically placed the frame on the back of the work ticket and placed a dots at the temporal edge of the lenses, and the nasal edges of the lenses, then connected the dots and measured with a protractor.

[hipoptical]

I have used several (including Harry's). I got similar results from each one, but they were slightly different. I am -475 -150 OD, -500 -125 OS and used myself for the trials. Any of the calculations worked better than standard fitting. The program from KBCo is good, and has charts to help you determine the correct panto and face-form for the calculations. I would use the charts from them, and a program like Harry's for ease of use.

[HarryChiling]

Thanks hipoptical, I don't know who it was but someone asked me for the source ode once, they were supposed to port it over to PHP, or Java, or JSP. Hint Hint someone ;). Anyway I have been working on a new project that should blow everyone away.

[Barry Santini]

Using wrap calculators optimally requires the following:

1. knowledge that the "starting" Rx is fully corrected for far distance
2. knowledge that the "starting" Rx is in accomodative balance (duo-chrome confirmed).
3. Knowledge of previously worn Rxs, and awareness of the overall Rx progression for that client
4. Knowledge of the "tolerance" for that client.
5. knowledge of the working fabrication tolerance for your wrap lens suppliers, particularly across different materials and powers (this requires the mandatory use of a reliable and accurate lensmeter that reads to 0.01D, and has abbe value adjustments).
6. knowledge that most Rxs will be *undercorrected* for myopes (20 & 10 foot testing distances) and that wrap calculators will, because of reduced vertex distances in wraps, reduce the minus power as well. This, I believe is the root cause of many wrap compensated Rxs NOT working out...the client is overplussed for distance driving because of compounding errors.
7. the ability to measure and validate frame wrap angle. Try this link to Pech Optical's excellent info on using a standard protractor below:
http://www.pechoptical.com/dispensing.htm Follow the link to the "protractor method"

Hope this helps
Barry

[Trevor D]

Hey guys (thanks for the awesome wrap calcs),

Why do I get different results from your guys' calculators?

Which witch is which?


Trev :idea:

[HarryChiling]

The calulator I made uses the true lens angle, Darryls takes the frame angle and frame measures and computes the lens angle. At some point I will update mine to include the more sophisticated calculations, but with a new baby here and things being hectic at work I wouldn't hold my breath.

[Samuel Jong]

I have had success, used my own, and basically placed the frame on the back of the work ticket and placed a dots at the temporal edge of the lenses, and the nasal edges of the lenses, then connected the dots and measured with a protractor.

Where can I get the protractor? Thanks.

[HarryChiling]

Use the one Darryl has provided, pretty straight forward

http://www.optiboard.com/forums/show...36&postcount=3

[Samuel Jong]

Use the one Darryl has provided, pretty straight forward

http://www.optiboard.com/forums/show...36&postcount=3

Thanks Harry.