The part of the bone i am going to remove now is very tough.Some times we have to use drill to thin it out and punch it. a good exposure is a must for Lacrimal sac surgery one should not be in a hurry to incise the Lacrimal sac, untill and unless it is nicely exposed this makes our job very easy and clean .And this is the area superiorly which has a tough bone, luckily here i am able to to remove it without using a burr. or a drill few more pieces can be removed to expose the medial wall of the Lacrimal sac. 