After quite a bit of heartache and worrying over why my betta is going blind, among other issues, I discovered something while scouring forums. What he has looks very suspiciously like something I ran across called "jewel eye" or "diamond eye" bettas, where their eyes become shiny/iridescent like their bodies, which appears to cause vision problems. Well, he's definitely got serious vision problems. According to the cup when I bought him, he's a dragon scale halfmoon (I wasn't so sure - he doesn't look much like the ones I see), and that they can be more prone to developing this. It looks SOOOO similar.
Anyone else ever run across this in your time of fish keeping? (He's my first betta and I've had him ~1 year now... not exactly an expert haha.)
Here is a picture of someone else's betta whose eyes look similar:
And of Jippers (his eyes are the same iridescent color as his body):