how to prove or check PALs have variable inset

[tktien]

Nowadays a lot of PALs company said their pal has variable inset, but actually how we can check for it?

[TLG]

Nowadays a lot of PALs company said their pal has variable inset, but actually how we can check for it?

Color me stupid but what does variable inset mean?

[chip anderson]

I think this means that you can turn the blank prior to grinding in Rx to allow for more or less convergence, or perhaps variations due to seg.ht. etc. affecting the actual reading "sweet spot."

Chip

[yayasister]

Tony,
Variable Inset refers to change in inset according to the add power of the PAL. Old style lenses didnt have that feature and were problematic for patients/customers with higher add powers. A lens with a +1.50 add is inset less than a lens with a +2.50 add because the eye converges more. These variations in inset are determinded and designed by the mfg. They vary from lens design to lens design and you should be able to check with your lab or lens rep if you want the inset info. for the brand lens you fit.

Hope that makes sense.
Lisa

[HarryChiling]

Each base curve from a manufacturer is designed to fit a range of Rx's in and for this range along with add power the manufacturer is able to come up with a optimal inset that the powers in this range would need. Drk just recently started a thread about DPD and NPD and their correlations. I think Darryl suggested a great inset rle of thumb, 1.5mm inset add 0.5 or subtract 0.5 based on + or - prescirptions respectively.