After having the opportunity to do countless heavy rain approchs at night into many of eastern canadas airports,I always found the most difficult part for me was how my depth and distance perceptcion would be affected for the landing,due to distortion from windsheild.Only one of many things you have to watch for ,turbulance,slipperyrunway,downdraughts,etc.But the really worst part was getting soaked while walking to pub after shift.