European prism notation

**VHB** · 05-08-2009, 10:26 AM

I just had this Rx emailed to me from Germany. I understand everything except the "cm/m" part.

R: +0,75 -0,25 70° Prismen: 3,00 cm/m B.180°
L: +1,25 -0,25 110° Prismen: 3,25 cm/m B. 0°

Any help will be greatly appreciated!

**wmcdonald** · 05-08-2009, 10:29 AM

This is the PD in CM.

**Aarlan** · 05-08-2009, 10:49 AM

Originally Posted by VHB

I just had this Rx emailed to me from Germany. I understand everything except the "cm/m" part.

R: +0,75 -0,25 70° Prismen: 3,00 cm/m B.180°
L: +1,25 -0,25 110° Prismen: 3,25 cm/m B. 0°

Any help will be greatly appreciated!

the cm/m part is another notation for a prism diopter.

1 prism diopter will deviate light by 1 centimeter at a distance of 1 meter...thus 1 prism diopter = 1.00 cm/m

AA

**Chris Ryser** · 05-08-2009, 12:15 PM

Originally Posted by VHB

R: +0,75 -0,25 70° Prismen: 3,00 cm/m B.180°
L: +1,25 -0,25 110° Prismen: 3,25 cm/m B. 0°

centimeters are 100 th of a meter........or............30 mm decentration

**DragonLensmanWV** · 05-08-2009, 05:37 PM

Those are base in OU?

**Oedema** · 05-08-2009, 07:42 PM

Originally Posted by DragonLensmanWV

Those are base in OU?

Base out

**rdcoach5** · 05-09-2009, 06:59 AM

If that is base out, how would they write base in?

**DragonLensmanWV** · 05-09-2009, 07:01 AM

Originally Posted by rdcoach5

If that is base out, how would they write base in?

I'm guessing 0 OD and 180 OS.

**Judy Canty** · 05-09-2009, 03:12 PM

Originally Posted by DragonLensmanWV

I'm guessing 0 OD and 180 OS.

And I believe you would be correct, at least as I understand from referring to my Ophthalmic Lenses & Dispensing by Mo Jalie. Second Edition, page 4.

**HarryChiling** · 05-09-2009, 04:35 PM

It's 360 degree notation people. Call your lab they'll understand it, or use your lensometers risley prism.

**chip anderson** · 05-09-2009, 05:56 PM

Actally I think the confusion here is using commas for decimal points and 3cm/per meter is three diopters of deviation (prism). the prism direction is stated in degrees (here 180 & 0) instead of up and down, in/out. As you know Germans like to state things precisely prism direction could be requested at any of the 360 degrees around the compass (or clock if you prefer.

Chi