A: そんなに見えない?
B: わりと...
The character B took off his glasses and A asks him "You can't see that much?" after B says he can't see past his feet.
B answers "わりと..."
how is "わりと used by itself?
In general, わりと is used in two ways:
When in doubt, "rather" in English vaguely covers both of these nuances. In your context, B is not only affirming A's statement but also suggesting his weak vision is quite significant. So it's something like:
A: "Do you really see that poorly (without your glasses)?"
B: "Rather dramatically." / "Worse than you might think." / "Yeah, actually."
Note that わりと is not a negative polarity item such as 全然 or まったく, so わりと見える and わりと見えない are both grammatically correct sentences. I'm assuming 見えない is implied after わりと.