Sophie, those flashing lights might be your vitreous detaching.
If you haven't had an eye exam in a while you might consider having one. It isn't always a problem, or is almost never a problem except the for the rather pleasant "shooting stars," but it can pull on the retina in a damaging way.
https://www.gettyimages.com/detail/photo/macerated-bone-with-osteoporosis-royalty-free-image/146592222
This is a photo of the spicula that support the vertebral endplates. The blood and nerve supply has been removed. Enabling a vision of those vermicelli-like structures which are some times thick sheaves. I like the photo because it shows how we can fracture myriad spicules before experiencing a compression.