Seeking definition of generator terms

[Armymedic]

Occaisionally, as an army medic, one comes across any of a great variety of concerns quite beyond the scope of standard training.

A soldier of mine, seeking to determine what the charcteristices of his prescription were, handed me his information.

I am amused that I can not find any precise definition to these following terms under the heading of Generator -- following the Tools section on his prescription, which terms Base and Cross, (curves,) I have come to understand. Also, a brief description of the set of terms under the DIMS section of his prescription are desired.

the terms are:
GENERATOR
Gen CT Fin CT True Curve Pseudo Curve
2.6 2.1 + 2.15 2.15


DIMS
A: 49.36 B:33.42 ED 33.42 DBL 20.9

I have posted this query undr the Progressive lenses forum, for his prescription is for Bi-Focals. However, let me add that this particular soldier's concern is for the ordering of a set of prescription sunglasses, to be used for distance viewing only.

As he is most concerned about the propr management of his expense, I am sure he would be quite relieved to know definately, what terms of a prescription, can be Isolated apart from those designating the details of the second, or reading focal.

With many Thanks
Keith.

[shanbaum]

First, please note that none of the information shown under "GENERATOR" or "DIMS" is part of a spectacle prescription. The parameters shown are the thickness setting for the generator (Gen CT) which includes an extra 0.5mm which will be removed in subsequent processing; the finished thickness of the lens (2.1mm, "Fin CT"); the lens' "True Curve", which is the surface power of the lens used for curve and thickness calculations; and the "Pseudo Curve", which is a curve value used for setting the thickness on the generator, used to determine the location of the front surface of the lens in the machine, which is necessary for the machine to be able to cut the back surface at a location that will produce the specified "Gen CT".

The "DIMS" are the frame measurements used in calculating thickness; A is the lateral dimension of one lens, B the vertical; the "ED" ("effective diameter") is the longest radius in the shape doubled, and the "DBL" is the distance between the lenses.

Some of these terms (especially "pseudo curve") are peculiar to the software (or person) producing whatever form you're looking at.

As I said, none of this is a normal part of an Rx; rather, this all is normally part of fabrication instructions, given an Rx, together with a particular frame and pair of lens blanks. The last is usually not known until the order reaches the laoratory.

[AWTECH]

The above answer tells you what information you do have, however what the solder needs for the distance visioin sunglasses is:

Sphere, cylinder, axis for both eyes. The pupil distance is also needed and if the prescription is strong he will also need the height of the pupil from the bottom of the frame.