How can I coloring an empty cell in a bounded datagridview?

Like the title says, I'm trying to coloring an empty cell in bounded datagridview.
I've got this code to coloring a cell with specitic value and is working well.
This code is in the DatagridviewCellFormattingEventargs.

If e.ColumnIndex = 5 AndAlso e.Value <= Date.Now.ToShortDateString Then
              e.CellStyle.ForeColor = Color.DarkGreen
              e.CellStyle.Font = New Font("Adobe Caslon Pro", 11, FontStyle.Bold)
End If

How can I change this code that in the same column and the cell is empty the backgroundcolor becomes red?

Thanks in advance.