Right, I saw the midwife yesterday and told her in detail about my multiple "incidents" of blurred vision and whatnot. She knew exactly what I was talking about, said it wasn't that unusual, and the deal is this: My uterus is getting huge, as it tends to do during pregnancy. And if I sit or lie in certain ways, it can press down on some major blood vessels carrying blood to the brain. So, the brain goes into panic mode at not having so much blood available, hence the hot flushes, shortness of breath, and blurry eyes. So I shall watch my posture, and sit forward if I feel it coming on again, and I only really need to worry if it's accompanied by headaches and/or swelling or puffiness of the limbs and extremities. Which it has never been, so it's ok!