Hide/Unhide row based on cell value

Hi, I am very new to writing VBA so for many of you this will most likely be a very simple question. I want to hide/unhide rows based on whether or not a cell have a value in it.
If L18 in blank then Row 171 is hided; if L19 is blank then Row 172 is hidden and so on to L168. I have it working for one cell/Row but how do I set it to do this for the range?
Here is what I have:

Private Sub Worksheet_SelectionChange(ByVal Target As Range)

Application.ScreenUpdating = False

Select Case Range("L18").Value = ""

Case True: Rows("171").Hidden = True

Case False: Rows("171").Hidden = False

End Select

End Sub