Why stop taking tamsulosin for a cataract operation?

My father, aged 85, has prostate cancer and is taking tamsulosin hydrochloride. he has an appointment for a cataract operation on his left eye and has been told to stop taking this tablet for 10 days before the operation.

Why has he been asked to stop taking this tablet?

What will be the effects on his prostate of not taking this tablet for a two weeks?