User blog comment:Elephant777/Long live the Queen, but how does she live? (Rexy)/@comment-17754282-20150418180629/@comment-17754282-20150420222409

We don't know whether or any of the dinosaurs ever actually were replaced with superior stock but it seems possible that any defects would have been corrected.

As for keeping Rexy alive, who knows? While her vision is incorrect everything about her seems fine. She's fully grown, she can hunt and eat and digest and breathe and everything else that an animal like her is meant to do. Maybe they just decided that the vision issue is something that they can live with? After all, if everything else is working fine, why tamper with it? Maybe they felt like she had a right to be in the park moreso than any other animal there.

And in any case, does the inability to see things that aren't moving really cause problems? In addition to making animals more accurate, some of the intention behind "improving" them were not actual "improvements" at all. There are several mentions in the books about potentially making the carnivores more docile. They may look in Rexy's visual impairment as an added bit of security - if you end up near her unprotected, stay still and she'll lose you and eventually go away. No obviously anyone getting near enough to Rexy for that to ever be an issue would indicate a far larger security issue, but in such a situation such a visual impairment may make the difference between life and death.