On occasion, usually in the morning maybe a month or more apart, I suffer from affects on my vision, bilaterally. It starts with a little spot that prevents me from seeing a small item, such as a letter in the middle of a word. It then progresses into a larger crescent shape that is bright, waving, or wiggling with my eyes closed, and disrupts vision around those areas with the eyes open. The whole episode then slowly passes as the waving lines progress down and to the side, and then out of the field of vision.