This may not be totally relevant to the OP post but I would like to share my mother's experience and what I learned from it.
My mother had a retinal detachment. I remember it very well. She asked me about her symptoms one Friday. The best way she could describe it was to say it felt like a black curtain was cutting diagonally across her vision in one eye. At the time neither of us knew what it might be and she left it for the weekend.
By Monday, the black curtain effect was larger and cutting out more of her vision so she made an appointment at the doctor, who referred her immediately to an eye surgeon, the very same day.
Unfortunately for my mum, by the time the surgeon saw her, later on Monday, the retina had detached completely. The surgeon explained to her that while he could reattach the retina, a partially detached retina would be much easier to repair than a complete detachment. She had the surgery to reattach it, but the surgeon warned her that trying to put a completely detached retina back exactly in place would be like trying to position a small pin in a tiny hole with the back of your shoe, or some such words, I don't fully remember. In other words, putting a completely detached retina back in its exact place would be extremely difficult. He said it would have been much easier if the retina was only partially detached, as it would have been on the Friday she mentioned it to me.
She managed to keep her vision, after surgery, but her vision was very impaired. Objects didn't line up correctly in her vision, objects seemed to be slanted and she mostly saw two of everything. It put a stop to her driving, but apart from that, she managed to live with it.
I say this not to cause fear but to mention that if a black curtain seems to cut across one eye, consider it an emergency situation because time is of the essence to get to a surgeon while the retina is still partially in place and not wait a couple of days until the retina has detached completely.
I hope my mum's situation might help anyone who might have this symptom at any time in the future.