Why do such vision problems occur? Recently, I have been bothered by regular flashes of light in the corner of my eye, which sometimes resemble a flash of lightning or a bright trace after bright light sources. This always happens during periods when I am stressed or tired. Could this be related to circulatory or nervous system problems? Also, should I see a doctor to rule out more serious diseases, such as problems with the vascular system or the retina? ?

Unfortunately a problem like yours can often be caused by migraines or other conditions affecting vision. Causes can range from normal stressful situations to more serious conditions such as changes in the retina. I've been reading about light flashes in corner of eye here on https://myvisioncare.org/blog/seeing-flashing-lights-in-the-corner-of-your-eye-causes-and-when-should-you-seek-help and have found that if these flashes have become regular or are accompanied by other problems such as deteriorating vision, seeing a doctor is the right thing to do. Be sure to check out the page that explains when to be concerned and how best to proceed in such situations.