It depends on the test evidence for the door - you will need to check this with the door manufacturer. As long as the door was fire tested with a glazing panel installed, then yes you can install a glazing panel, up to the same size (in area) that was tested, and in the same place in the door leaf.
Lorient's systems have also been tested in typical fire rated door constructions, and we hold extensive test evidence ourselves which allows for glazing panels to be fitted, up to certain sizes - please refer to our Fire Resistant Glazing Systems page and brochure (available to download from this website) for more details, or contact our Technical Services team on +44 (0)1626 834252 if you would like to discuss your specific application.
If you are installing the doors on site, do also remember that cutting apertures for glazing (and other apertures) in a fire door on site is not permitted under the BWF-CERTIFIRE Fire Door and Doorset Scheme, even by an approved aperture cutter. This should only be done at an approved BWF glazing centre. You may also find this link to the BWF helpful, and particularly the fact card on Fire Resistant Glazing.