I had flashing lights and twinkles/glitter in my vision field. It comes with optic nerve involvement due to the swelling from PE/PIH.
For me, the flashing lights looked like someone was taking my picture w/ a camera, only there was no camera.

Sometimes I'd sit in the dark and have these constant flashes... sometimes the flashes of light wriggle around in a circle or sweep across like a wave. I thought I was losing my mind when it started. Also, once in awhile I got pretty little glitters/twinkles when my BP was high... It looked like pixie dust if you watch Tinker Bell movies with your little kids.
The ringing in the ears - its called Tinnitus, I have the luck of a hearing loss with tinnitus that occurs randomly but can last for hours at a time. I'm not aware of tinnitus in pregnancy but that doesn't mean anything as I'm not a dr.
In either case, vision issues or tinnitus, let your OB and/or MFM know... the visual issues do need further examination.
2005: PE/IUGR pregnancy with Daughter, born 40+2 induction. Diagnosed with Sensory Processing Disorder (or Sensory Integration Dysfunction) in 2010. Diagnosed with ADHD in 2011. It's getting better with OT and treatment!
2009: PIH pregnancy with Son, born 38+5. Diagnosed in 2011 as Developmental Language Delays, Social-Emotional-Communication Delays. More testing Nov. 2011.
2011: I'm undergoing neurological testing. Praying for the best!