DISCLAIMER: Absolutely DO NOT ASK or otherwise bother John Flansburgh about this. This theory is presented for CONSPIRACY PURPOSES ONLY. Even if I'm right (and I totally am) you are a stranger; don't bother the man about the details of his medical history.
John Flansburgh hasn't been nearsighted since 2012 and I'm going a little Pepe Silvia over the fact that nobody else seems to have noticed this.
Crash course on how this works:
If you can only see things that are NEAR to you (and anything further is blurry), you are NEARSIGHTED.
If you can only see things that are FAR from you (and anything closer is blurry), you are FARSIGHTED.
Glasses lenses fix farsightedness by curving outwards (a convex lens). This makes your eyes look larger, magnified. Here's John Linnell wearing reading glasses to fix his farsightedness. Note how the edge of his face as seen through the glasses is distorted outwards.
Glasses lenses fix nearsightedness by curving inwards (a concave lens). This makes your eyes look smaller. Here's John Flansburgh wearing glasses to fix his nearsightedness. Note how the edge of his face as seen through the glasses is distorted inwards.
Because these lenses have opposite structures, a pair of glasses can (almost always) only correct one at a time, unless they are bifocals. If a farsighted person puts on nearsighted glasses, it makes their vision worse. If a nearsighted person puts on reading glasses, it makes their vision worse.
Got it? Good! Now here's a test: one of these pairs of glasses is not like the others. Do you see why?
2012 and before (Note the visible glasses distortion!)
Hints at corrective eye surgery:
2013 and afterwards (Note the COMPLETE LACK of glasses distortion- are these just clear sunglasses??)
Here's a side-by-side. Are the glasses on the right doing ANYTHING, do you think?
Actually, in some cases lately, there *is* visible lens distortion... that of mild reading glasses. (Example 1) (Example 2) Which STILL is evidence in my favor, because if you're already nearsighted enough that you lose your glasses when you take them off (which, same here), wearing reading glasses will give you a wicked headache and leave you walking-into-walls blind. Not something you'd want to be doing while walking around and playing an instrument.
Conclusion: John F has much better eyesight than John Linnell at this point, but because he accidentally made being a bespectacled guitarist his entire identity in the 80s, he's decided to Clark Kent his way through life from here on out. Godspeed, you funky old guitar man. Your secret isn't safe with me, but that's alright, because nobody will believe me (or care).