Recently white spots in my eyes looks like lace lasts 1 min. 3 or 4x also dizzy spells when lying down. cataract operation 10 years ago. serious?

Yes very serious: You may have TIA ( transient ischemic attacks) a warning sign for impending stroke , you have to see your doctor immediately , or better go to er & call , for work up and treatment to prevent a future stroke.

Check it out!: What you are describing seems more like a blood pressure related item, systemic issue, rather than the eyes. I would start off with the primary care doctor!