Are all or any types of brain tumours visible in an eye exam? as in, could it be seen or show as pressure on the optic nerves?

Sometimes: Some brain tumors are large enough to increase the pressure inside the skull. That pressure can be transmitted to the optic nerve and show up as papilledema and swelling. There are other more common causes of papilledema and swelling. An eye exam can show a possible brain tumor but often will not. Sometimes tumors are also found if they affect a person's visual field.

Some: Tumors that compress the brain or cause edema can result in papilledema or swelling of the optic nerve. Not all tumors will cause this though most larger lesions will. Pituitary tumors because of their location can be associated with other visual changes. Papilledema is an indication for a brain scan.