[Robh (Rob)]

Hi Peter,

Here is a fairly safe way to measure your pupil size.
Make a template similar to the one below using cardboard.
The width between each of the slit pairs is in millimetres.
Cut out the template using a stanley type knife carefully cutting out the slits. Just don't cut yourself.
The fold is to give it a bit more rigidity.

Procedure:
1. In a pitch dark room put a subdued light about 3 to 5 metres away. A red light torch turned down is ideal.
2. Put the cut template on the bridge of your nose with the fold forward.
3. Close one eye and slide the template slits past your open eye. I usually work down from 9mm to 3mm.
4. At the higher end, you will only see light through one slit. Move down until you just see light through both adjacent slits. That is approximately your pupil size.

Regards, Rob