A patient walks into an optometrist’s office.

The optometrist starts the eye exam and casually asks her if there’s any particular reason she came in for a checkup.

“Doctor, I think am having hallucinations. Every time I open my eyes, I see really dark things. Evil. Malice. Hatred. Plague. I am seeing the worst in everything. Nothing looks like it used to. It’s as if everything I see is shrouded in darkness.”

The optometrist sits back from the patient, confused.

“That’s interesting,” he said, “because from what I can tell, you see 20/20.”