Animal Mother,
The question you ask is complex and beyond the ability of anyone on this board to answer accurately. I recommend that you contact Diver's Alert Network at Non-Emergency Medical Questions
1-800-446-2671 or 1-919-684-2948, Mon-Fri, 9am-5pm (ET). They have medical professionals who can assess your situation in its totality and give you an educated opinion. Your neurologist/neurosurgeon may also be an excellent source of information for you.
They will probably ask specific questions about the type of pituitary tumor, how it was treated, and medications you are currently taking. It is my opinion that the issues are probably greater than whether your eyesight is adequate.
Good luck in your information search. Hope you are able to explore the amazing world underwater.
dolphin64