Can ocular migraines be a sign of something dangerous? my husband has a long history with migraine headaches, but lately getting more ocular migraines only..should we be concerned?

The "ocular migraines" are typically the aura portion of classical migraine events. The absence of pain does not imply absence of migraines, just a shift in the pattern. If these are frequent or prolonged, this would compromise visual acuity, and it could be dangerous to drive. Preventative medications are available. A neurologist can help with management.