Hilchos Issurei Mizbeiach 2:11

If an animal was slaughtered and then found to be a treifah, it must be taken to the place of burning. This is also the case if an animal is found to be missing an internal organ even if this doesn’t render it a treifah, such as if it has just one kidney or if the spleen was removed. These animals may not be brought on the altar and must be burned. This isn’t because it’s blemished, because such unseeable defects are not considered blemishes. Rather, an animal missing an organ may not be brought as an offering because Numbers 28:31 specifies that “They shall be perfect for you.” An animal with an extra organ is the same as one missing an organ, so if an animal has three kidneys or two spleens, it is invalid.

Hilchos Issurei Mizbeiach 2:12

A permanent degeneration of the optic nerve means that an animal was observed for eighty days and it was determined that it couldn’t see. It is inspected three times: on day 27 from when the trouble was first noticed, on day 54, and on day 80. If the animal’s vision returns temporarily, we count from when it stopped seeing.