A Select Case Statement may be more eloquent. Also, if using an option group, it is helpful to use the Wizard to set it up.
Maybe something like the following is what you are after...
Code:
If Me.Choice.Value = 1 then 'This is the option Option Box
[Forms]![Formname]![Subformname]![fieldname].visible = false
Else If Me.Choice.Value = 2 then
[Forms]![Formname]![Subformname]![fieldname].visible = True
[Forms]![Formname]![Subformname]![SomeOtherControl].visible = false
Else
[Forms]![Formname]![Subformname]![fieldname].visible = False
[Forms]![Formname]![Subformname]![SomeOtherControl].visible = false
End if