One day in 2015, Liz Rundzieher stopped at her refrigerator and looked at the Amsler grid hanging there to test her vision—something she did often. But this time, instead of seeing the grid’s straight lines, running up and down in the shape of a square with a small circle in the middle, she saw something new. Something different. She covered her right eye. The lines were straight. She covered her left eye. The lines were wavy. Rundzieher, 74, of Houston, knew what she had to do. “I didn’t wait. I called [the eye doctor] that day to make an appointment. And the minute I said to the appointment service what that was happening, they were very good about getting me an appointment quickly,” she says.