I have searched the web and no application is available to view the OPV file formats which means this is a proprietary format and only the applications released by Optec. If the viewer application is not working on your computer, then you need to either apply a compatibility tweak or simply contact the Customer Service on the official website: http://www.optec.com/led-signs-customer-support/
To apply a compatibility tweak, right click the view application and go to Properties > Compatibility. After this, select a previous version of Windows from the list and tick the Run as Administrator, then launch the viewer again.