question for Darryl

[harry a saake]

much is always made about the minumun fitting heights for progressives, but in a lot of designs should there not be published a maximum height also

[YrahG]

Sorry not Darryl, but I'll take a crack at it.

Most manufacturers recommend 9 to 10mm minimum height from the fitting cross to the top of the lens. A lot of frames today have the bridge soldered high on the eyewire, which makes many smaller B size frames able to fit short PAL's but it also means that now we need to watch the distance zone.

[William Walker]

I hope the popular frame styles don't get large enough that I will ever have to worry about a max heighth!:)

[Darryl Meister]

Ultimately, it really depends upon the visual requirements of the wearer. A patient wearing the lenses part time primarily for reading may be less concerned about distance utility. Also, a hyperope may be less sensitive to the size of the distance zone than a myope or feel less need to "tip" the chin down to see clearly at distance.

In any case, this value is arguably less critical than the minimum fitting height. That said, as a rule of thumb, when asked we generally recommend at least 7 mm of clearance above the fitting cross for short-corridor progressive lenses and 8 mm for general-purpose lenses, but you would want to consult your progressive supplier of choice.