swim before (one's) eyes
To appear in or cloud one's vision. Usually said of floaters (clumps of fibers in the eye) or rings, spots, or flashes of light (called phosphenes). I stood up too quickly, causing flashes of light to swim before my eyes. A: "My daughter's had these floaters swimming before her eyes recently." B: "Isn't she a bit young for that to be happening?"
swim before someone's eyes
Fig. [for something, such as spots or visions] to appear in one's field of vision. I was getting feverish and spots swam before my eyes. Visions of total destruction swam before my eyes as the bus skidded in the snow.