Can eye doctors know if you have a brain tumor or any other brain disease by an eye exam?

Just suspicious: A good eye specialist can use the eye exam as a window into the brain. However, the exam can only suggest that some pathological process is occurring. Once an abnormal feature is discovered, specific tests need to be performed to investigate the cause. This usually involves brain imaging, spinal tap, specific blood and spinal fluid analysis, even brain surgery.

Possibly: What can be noted is what is known as papilledema. This is swelling of the optic disc due to something causing increased intracranial pressure. It can suggest something is causing pressure but it does not tell what. Hope this helps.