Hi. Is it safe to give my pregnant dog Optrex for infected eyes?

Ask your vet.

Can't help thinking that a less dismissive reply might be more helpful? There is more than one type of optrex eye drops and they contain different active ingredients, so would be used for different problems.
Eyes are of course very delicate and easily damaged which is why it would be best to let the vet have a look at them, then you will get the correct drug and hence the most effective treatment for the problem.

Optrex Infected Eyes contains an antibiotic (chloramphenicol). 

Chloramphenicol should not be given to a pregnant dog:  http://www.diamondbackdrugs.com/chloramphenicol-medication-for-pets/

I would try bathing with salt water regularly and if that doesn't work in 24hrs, see your vet for a med you can safely use during pregnancy.  Note that vets are not used to dealing with pregnant dogs, let alone pregnant dogs with eye infections, so I would double-check whatever is given is safe for your dog in pregnancy via trusty google.  Which has its uses.