The Screen
How can the subject avoid being captured by the look?  The answer is the screen. 
1. Lacan explains that since we know we are being seen, we can manipulate the "self" that is seen by the look (of others, including objects): "Indeed man knows how to play with the mask as that beyond which there is the look.  The screen here acts as the site of mediation" .
2. Also, the screen also helps us to see objects: "an object veiled from sight by an over-intense light can be discerned only if a screen is interposed which partially obscures the light and/or the observing subject".
So, the screen works both as a way to manipulate what people see about me and allows me to see objects yet stands in the way from me ever having the objects fully .  Lacan explains this dual function, "The subject presents itself as other than what it is, and what it is given to see is not what it wants to see".

more about Lacan