[@misssgodfrey]

@misssgodfrey asked the Naked Scientists:
   
When I get really annoyed my Mum says my eyes 'flash'- is this possible or is she just seeing things?I've always wondered..

What do you think?

[RD]

The "flash" may refer to momentarily exposing the white (sclera) of the eye above the iris ...
http://www.face-and-emotion.com/dataface/facs/manual/AU5.html

This raising of the upper eyelid exposes more of the eye, so a momentary catchlight is also more likely,
 (which could be described as a "flash" of light).