I have never been happy with the other eye replacers for New Vegas. Either they were cartoony and bright, added a massive list of jarring colours or were just to complicated for their own good.

So I set about to do something similar to my mod from Fallout 4 and rework some of the textures to fit New Vegas.

It turns out that New Vegas uses a completely different texture layout and mesh to Fallout 4 so I had to fairly extensively modify the iris and completely remake the Sclera.
I also discovered that NV does not use a normal map at all or utilise an environment mask for the eye texture. So I have ported them over and modified them from my Fallout 4 mod. I had to add the new texture paths to the Nifs as well, so that's why there is a mesh folder included here.
The mod includes full remakes of every vanilla eye texture in a consistent and lore friendly style. I have tried to stay close to the original colours whilst adding a little more detail so the textures look more distinct from each other.

The textures are all 512x512 in size up from 128x128 in the vanilla game. The reason they are not larger in size is simply because they do not need to be. The distance you see eye textures from means there is no appreciable difference from a 512x512 to a 1024x1024. You don't need 4k eye textures. Period. The size of the mesh in question and relative distance from the player dictates the best texture size to use to be in line with the games overall texel density. 

Screenshots are taken with my character overhaul TTW NPC Overhaul installed.
I use no ENB or reshade.

Thanks to LogRaam for some of the source textures I used for the Iris.