I hardly need it, but it needs surgery.

This is a terrible photo, as it was taken at night, without the flash, through my bedroom window. I'm fairly certain that this is my kitten Cally's sister, as it's the same age. She's a feral who eats on my porch every evening, although I haven't yet been able to trap her. Her left eye is dead and is spreading infection down her face. She desperately needs surgery, but she just won't get into the trap....