A retained lens fragment is a relatively common occurrence after modern day cataract surgery. We are able to use small 2 mm incisions to perform cataract surgery because we break the cataract up into many small pieces. Remember that the human crystalline lens (and cataract) has dimensions of about 9 to 10 mm in diameter and 4 to 5 mm in thickness. And all of that lens material has to come out of an incision that is usually between 2 and 2.75 mm in width. Even in a case like this where I show you the end of the cataract case (with great dilation) and you do not see any lens fragments, you can be surprised on post-op day 1. The retained lens material can hide in the sulcus, behind the iris, or in the capsular bag equator. And when exposed to the aqueous overnight, it swells and often presents itself in the anterior chamber on post-op day 1. Previous posts and videos have explained the management options. In this case a return trip to the operating room to aspirate the fragment is warranted. This video shows both the original cataract surgery and the return to the OR. If you perform cataract surgery routinely, you will certainly encounter this situation many times over the course of your career.