I'm sorry I didn't answer all your questions.

Collagen plugs are put in the tear ducts.
Which there are 2 in each eye. One upper
one lower and are located in the inside 
 >   <    of your eyes.  You can see them in a mirror if you look close. 

Collagen dissolves over a 3 month period. They use collagen to plump up lips.

Used this way it's been described to me as putting a sock in a bathtub drain. The water will still drain but very slowly. 
So what it does is keeps the tear ducts slowly tearing so the eyeball is more moist and is kept that way for up to 3 months. Then they need to put in new plugs.

When the scar tissue is removed =MOST=
eye docs let it just heal over and YES this creates more scar tissue in time. 

My doc refuses to do this. He will remove the scar tissue and graft a piece of tissue from under the eyelid which I explained in my 1st post about this. ;)

Grafting should also be done with lasor eye surgery. But it is rarely done. My doc does a lot of these surgeries to repair goofs of other eye docs. No the area of my scar tissue on my right eye only is too large to be done with a lasor. 

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I'll just go ahead and google and see what collagen plugs might be and the incidents of scar tissue returning. 

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Btw, I emailed and maybe it was overlooked, but curious, what are collagen plugs? Also if they remove the scar tissue won't it just come back even more like it will on most places in our body?