Does anyone know in which way a light is more effective wenn using against a attacker to give you those few seconds to run or fightback? Do you blind them just a short moment, like with the a camera flasher. Or do you keep the light buring on his eyes for a longer moment so his eye's gets used to the bright light and loses it's night vision totally ?

If you are about to be attacked I would recommend something better than blinding him. Blast him with a face full of pepper spray and then sit on him while you are dialing 9-1-1. <img src="/images/graemlins/smirk.gif" alt="" />

well pepperspray, teargas, taxers, etc are illegal in my country. The legal selfdefence "weapons" you are allowed to use are sprays ( the only spray that actually block vision uses foam for that purpose... ), personal alarms ( CO or battery powered ) and the flashlight.

Also i think the actual chance of getting attacked is too low for me to carry a specific selfdefence "weapon", that is proberbly not very effective anyways. A high power multipurpose flashlight is already part of my EDC, so it's more suited in my situation. It also draws less attention than the alternative´s.

Personally the only way I would rely on a flashlight for self defense is as a club or yawara stick. "Blinding" light as an effective defense tool is a marketing myth, and thats putting in politely.

I doesn´t work that way. When it´s dark and you flash your light a person would have a reflex to close the eyes for a short moment and turn the head away. That will limit the blinding effect and your time to react. The time span is closer to one second than to a few seconds. Getting the flashlight ready for use may cost you more time than you get from using it.
Marc 'Animal' McYoung has a pretty good article about how to avoid getting into a selfdefense situation. The site is about knife fighting but you can skip that part if you´re not interested in that.

well i know enough things about staying out of trouble, but i was just thinking of a possible other use of my EDC flashlight. Ofcorse i forgot to add the 3rd option "or doesn't work at all" or something...

The best blinding light to use for self defence is the muzzle flash from a well tuned .45 <img src="/images/graemlins/wink.gif" alt="" />.