Bright surfaces pulse effect in vision.

I am observing pulsating effect in vision when I am at outside on sunny days. First few minutes nothing. It's starting after specific time when I am outside. Three months back got eye big flashes for one time only. And then noticed sudden floaters next day. Checked with ophthalmologist, no tear or hole in retina and compound astigmatism per report(two months back from now). As of now seeing lite rainbow halos around street lights when having black background,Long beams for vehicle lights, pulsating in vision on bright white surfaces (roads and white walls), floaters, white spots when closing and opening eyes ( not at after opening and closing eyes) occasionally. Using glasses from last 15 years. Software engineer by profession, seeing screen 9 hrs per day. I am scared with these symptoms. Please help. What actions required?