NcytryBeen, I had my eyes go ballistic on me on a long road trip a few yearrs ago. I found out a day and a half later the cause of it, that was the first warning sign that I was heading into a significant, near heat stroke. Got too hot and even drinking a lot of water could not off set it. My temperature went up close to 104 just before I started prrojectile vomiting.
Do not ignore that warning sign of vision issues, it is a very serious warning sign you must pay attention to. Stop and get a good quality body temperature thermometer. Check your temperature frquently to make sure it is not elevated. If it is stop and check into an air conditioned motel room. Take a long cool water bath and rest up until your temperature returns to normal before resuming your trip.
The older we get the more heat sensitive we become. So be careful on road trips, it can sneak up on you.
This goes for all of us nomads, travel with a thermometer in your first aid collection! Use it if you start to feel a bit odd or get sudden changes in vision, feel nauseated, dizzy. Etc. Those are early warning signs of heat exhaustion and a rise in your temperature helps confirm that is what is happening to you.