I am 68 years and my eye doctor wants to do tear duct surgery which will require thirty minutes of general anesthesia. i am concerned about cognitive problems after surgery. is my age a problem for anesthesia or do think it would be safe?

If you are healthy and have no cognitive issues you will be fine. But discuss your apprehension with your MD and the anesthesiologist.

To experience a cognitive consequence due to 30 minutes of general anesthesia would have to assume either a catastrophic allergic reaction, a cardiac arrest, a massive pulmonary embolism, or profound hypoxia. All of these are exceedingly rare. Suggest you have a conversation with your anesthesiologist.