In the waiting room of the local eye hospital (US) I encountered someone (else) who had GCA. She lost the vision in the upper half of the left eye. I asked her about her symptoms and she doesn't really remember anything which alarmed her. She described that the vision was "shaking." She started with PMR, was tapering and was hit with the partial blindness. I have had what I describe as shaking "flashes" of arched black and white variegated tiny fragments. Sometimes they are pastel and black. But there is always "shaking." When I increase prednisone, (or before I was diagnosed when I took prednisone), after about 3 days these episodes stopped. The doctors wonder if my symptom is one of a migraine headache but without the migraine. However, they up the prednisone, none the less. So be careful. I'm wondering if this is also a dangerous symptom along with very temporary loss of vision, or large black spots, or a "curtain" descending down or across the eye. No question here. Just a caution.