How to replace the battery in an Essilor Digital CRP pupilometer?

[jdnisson]

I just bought a used Essilor digital pupilometer (REF:X81701) and am trying to figure out how to replace the battery. Can anyone tell me where the battery compartment is and how one opens it?
Also, is there an on/off switch? Does the forehead brace turn it on an then one just waits for auto-off?
Thanks in advance for any help.

[CME4SPECS]

There is an internal mercury switch that turns it on when you have it in the measuring position, when finished using it, turn it over and it will go off. The battery compartment should be on the side near the point that you would look through when measuring.

[jdnisson]

Thanks.