-> I know that a cat can adjust the incoming light in the eyes 
-> by open or close the pupil. 
-> The other day a used a flashlight right in the eyes of one 
-> of the cats and normally I think that that would have blinded 
-> him but reacted at my movement just beside the lamp. 
-> Why wasn't he blinded? 
  
Apaet from having strangely-shaped pupils, cats' eyes work pretty much 
as our own. 
  
If you had been in the cat's position, with a flashlight shining into 
your eyes and someone moving near it, would you have seen the movement? 
I think you would. The light would have dazzled you a bit (not 
"blinded"), but not enough to prevent you from seeing movement. 
  
It's a bit like driving at night. The headlights of oncoming traffic 
can be annoying, but they don't prevent you from seeing the road ahead. 
  
Changing the size of the pupil is only one of the mechanisms by which 
eyes adapt to varying light levels. The sensitivity of the retina 
changes, and does so locally, so part of it can be more or less 
sensitive than the rest. Shining a light into an eye makes the bit of 
the retina where the light hits less sensitive, but other parts of the 
retina would remain sensitive. 
  
                            dow 
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