Let’s dig deeper.
When a pilot sees an Aviation Medical Examiner (AME), there are three possible outcomes: They can get their renewal, they can be banned from flying planes, or their pilot license can be deferred.
A renewal is good for a certain amount of time. It differs according to your age and the classification of the pilot. Commercial pilots have more frequent renewals than, say, someone driving a piston aircraft. And older pilots have their medical clearances expire sooner than their younger colleagues.
But regardless of when the medical exam is due, all pilots are supposed to report to an AME if they develop a new health condition, no matter where they are on the AME timeclock. They usually don't, but policy is that they should.