Dr Park has been blinded by exposure to solar radiation. Lt Johansen says, "there's no treatment ... her corneas were burned by ultraviolet radiation." There is a treatment for this: back on Earth, corneal transplants are common. It's possible that Lt Johansen means that Dr Park's retinas were damaged; there would be no treatment for that. (In addition, corneal damage would present as severely blurred or cloudy vision, not complete loss of vision.)