In cases where the pupil does not dilate fully, it can be difficult to see the entire capsular bag to make sure that all lens material has been removed. The capsular bag diameter is about 9 mm in the average eye, so if the pupil dilates to just 5 mm, there will be a significant area under the iris that will not be easily visualized.
The solution is to use the chopper or second instrument to lift the iris in all quadrants so that we can inspect the entire capsular bag. This is most easily done after the IOL has been implanted and the eye is still full of viscoelastic. This helps to minimize the risk of a retained lens fragment.
Click below to learn how to check for hidden cortex in cataract surgery: