Okay, so I will admit I was inspired by another purple eyes mod here on the nexus. However that one was a simple replacer for one of the default eyes which I didn't like. So, I extracted the texture from the Skyrim BSA and made my own standalone eye mod. 

Now it doesn't stop there. The main mod uses my own personal edit. Basically the white part of the eye has been changed to a light shade of purple to match the way the normal red eyes look. However if you prefer to have Karliah's eyes where there's some white then use the optional texture. :) 

Installation: 
Use either the NMM or simply drag the files into your Data folder. If you are using the optional texture then simply override the main files textures and you're good to go! :D