I have some light fixtures that are currently used and covered with blind plates in the corners of a concrete ceiling room. I was wonder if there was anyway to convert those existing light boxes to recessed lighting. The wiring is already done but i imagine id need to get a deep hole.
If the boxes in the concrete are round boxes, there are LEDs that give the look of recessed lights. Here is a link to a source for them. They can only go in a box with a few wires in them, they fill it up pretty well.
From you comment that these are indeed junction boxes in a concrete ceiling, I would answer your question by saying...
No, it is not worth it to change them to recessed lighting.
There are many very attractive fixtures manufactured to attach to a standard octagon junction box on the ceiling. Some will mount very low profile if you are worried about head clearance. Most come with mounting plated that can adapt to a device box also. If these are 4" square boxes you will need to modify a blank plate or buy an adapter plate for a light fixture.