Do only if Cell not empty on range

Hi all

I am running this code:

With Range("O:O")
With Target
If .MergeCells Then Call Notmerged Else .EntireRow.AutoFit
If Not .MergeCells Then .RowHeight = .RowHeight + 5
End With
End With

It's running fine, except I would not like it to run if the value in col. O is empty
I should incorporate this in this line

If Not .MergeCells Then .RowHeight = .RowHeight + 5

Any ideas?

Thx
FD