It's interesting that you consider this to be example of evolution, as does the article I have reproduced below (my emphasis added at the end). A creationist would argue that it's just another example of a trait that was useful in the past, but has since been lost (loss of information is not evolution but devolution as has happened with the dog kinds for example). Remember, creationists don't argue against changes, sometimes quite dramatic changes, but only against one type of creature changing into something totally different. So this is just another example of something that has nothing to do with supporting evolution being used to try to show otherwise. No wonder those of us who don't accept [macro] evolution are highly sceptical about said theory.
Here's the article...
"Long ago when we were more dependent on our sight for hunting and/or defending ourselves from various animal attacks, we
had a third eyelid that could move sideways and was half transparent so we would not waste valuable time of sight as a result to blinking.
At least this is what is thought by most scientists and biologist. The proof of this is all around us. A lot of different birds, reptiles, amphibians, and fish have this weird third eyelid which is actually called the
nictitatingmembrane. Even though it is not as common, the nictitating membrane has been found on a
number of different mammals. The only primate that has the nictitating membrane is the
Calabar angwantibo. Therefore the chances are big that previous primates, including an older version of the Homo sapiens, had it as well.
What is thought to be the remains of this third eyelid on us humans is the plica semilunaris. This is the pink stuff located in the corner of our eye and it is similar to the nictitating membrane that other animals have today. This is an additional proof to the theory.
Today the muscles that used to control the nictitating membrane are completely dispatched. No one is known to be able to use these muscles anymore and the reason why not is most likely because at some point in time, supposedly when we started living more and more in groups, we didn’t need it anymore.
As evolution tells us, anything that has no use goes bye -bye." I could substitute this with, "as creation science tells us, anything that has no use goes bye bye" and it would make just as much sense.