Office calculator?

[Becko Istatkoff]

Hello,

I was looking for an Office lens calculator. I don't find any so can anyone explain what is the relation between degression and distance?

Ex: +1.0 Add 2.0, how do you calculate biggest viewable distance for Interview 0.8 (for power +2.2 in this case)?

I hope I explained my question correctly.

[HarryChiling]

Hello,

I was looking for an Office lens calculator. I don't find any so can anyone explain what is the relation between degression and distance?

Ex: +1.0 Add 2.0, how do you calculate biggest viewable distance for Interview 0.8 (for power +2.2 in this case)?

I hope I explained my question correctly.

The interview lens comes in two digressions -0.80 and -1.30. You can take the patients reading prescription and add the digression to come up with the power in the top intermediate zone.

A good rule of thumb is to use the 0.80 digression is the add is +2.00 or below and the 1.30 digression if the add is above the +2.00.

The claim by Essilor the manufacturer of the Interview is that the lens similar to a SV lens and requires no adaption time, having such a low digression power means less blending then a progressive style lens, also a digression starts the design in the bottom of the lens and blends towards the top which means the reading is going to be emphasized and have a large blend free periphery.

[D_Zab]

The interview lens comes in two digressions -0.80 and -1.30. You can take the patients reading prescription and add the digression to come up with the power in the top intermediate zone.

To put this in the terms of your example:

OU +1.00 Sphere with 2.00 Add would have a reading prescription of +3.00. You subtract the 0.80 digression from it which results in a +2.20 power in the upper portion of the lens.

If you are asking how far someone would be able to see when wearing an office-type lens I generally tell people between 5 and 7 feet (1.5 - 2 Meters), but that may vary depending on the design.

[Becko Istatkoff]

Hello,

thanks for taking the time to explain this. I know what Interview is and I know how degression works (I know how to test it). What I don't know and what I am looking for is how to calculate the distance. There must be some dependancies and I am not asking for a rule of thumb but the rule of the physicist.

For example you know that for contact lenses you have to substract/add 0.25 for powers 2.5 - 5, and 0.5 for above, but it's always nice to know the formula that led to that conclusion.