Answer
Johnny's visual problems are due to pressure of the pituitary tumor on his optic chiasma.
Work Step by Step
Johnny has developed a very large pituitary tumor. It has grown up into his brain and is pressing on his optic chiasm. This is the cause of his headache and his vision problems. If Johnny does not get expeditious effective treatment, not only will his headaches and his visual problems get worse, he may develop high blood pressure, heart damage, and Type 2 diabetes.
