-IMPORTANT NEWS-

I have released a new and improved version of this mod idea, available at https://www.nexusmods.com/skyrimspecialedition/mods/41014/
I'm leaving this version up for posterity - in case anyone has a savegame that depends on this version. Or I guess for those who don't want to use RaceMenu and don't care about Beast Race support.
The description below is still largely accurate, except for any innacurate mention of tools/mods that haven't been updated to SSE, as well as any mention of making this mod have support for other Eye Mods. Those are all handled in the new verison.

-Introduction-

I found it rather annoying that you could select an eye set that makes your left eye blind, but there wasn't the equivalent for the other eye, or even for other colors. So I set out to change that, and so much more.

That's right! I'm back to modding. Thanks to some help from a good friend of mine, I was able to replace my video card early this year. Now
that SSE has come out and my computer is back to running in tip-top shape, I'm back in the saddle and ready to get to modding. Hot on the heels of my other mods Morrowind-Style Soulgems and Less Annoying Lydia, I've decided to try to tackle the conversion of my most ambitious 32-Bit Skyrim mod to SSE.



Using the power of xEdit for SSE, and a little digging in the CK, I broke apart each possible eye color into left and right parts, and then created several hundred new eye selections that each use some combination of the colors. Since it's only changing how the eye selections work, it should be compatible with any texture replacer mod. It even removes racial restrictions between Human/Elven eye sets! Over 1,000 combinations are now possible, without adding any new textures! Want to make your Nord have his left eye be Orcish and Red, and have his right eye be Blind? Go for it!

Using the power of Racemenu (and with a lot of help from its author, expired6978), this mod adds two new sliders that control each eye. Sadly, SKSE has not been ported yet, so this feature has been disabled for now. Once Racemenu and SKSE are fully functioning in SSE, I'll re-add the awesome sliders function so it's much easier to select eyes.
Now with Beast Race support! Using some new meshes, Beast Race eyes are now able to be separated into left and right. Beast Race support has broken with the SSE release, as the meshes are not the proper format. Once I get the meshes converted, the Beast support will come back right away. If anyone knows how to convert head part meshes to SSE, please let me know. I tried the spell batches in the beta6 Nifskope but they still will not appear properly in game.

-MOD NEWS-

Version 1.1 is out now!
What's New:

• Snow Elf eyes and a second variety of Vampire Eyes!
  

- PLEASE READ THE ENTIRE DESCRIPTION BEFORE DOWNLOADING -

You should always know exactly what you're downloading and putting into your savegames.

-What's the difference between this and other eye mods?-

Other eye mods add new textures, or add completely new eye models. This mod doesn't add any of those; it adds new 'eye sets' created using the textures already available in vanilla Skyrim. This also means that this mod works with re-texture mods that change vanilla eye colors.

-How do I use it?-

Just install it and the eyes will appear in your slider. Note that there will be several hundred options now, so dragging the slider with your mouse will slide through dozens of eyes very quickly. They're organized so that all of the options for a given Left eye will appear in a row, so just slide the bar around until you find the left eye you want, and then use your left/right buttons to find the other eye texture you want.

If you're using the version with the new sliders, you need to have RaceMenu installed, first. Two new sliders will appear towards the bottom of the eye customization list. Moving the “Left Eye” slider will change the texture of the left eye, and moving the “Right Eye” slider will change the other eye. To prevent issues, I’ve made all Vanilla eye types “Unplayable” in this version to prevent them from showing up in the regular slider. If you have a mod that adds entirely new eye types, those will still show up in the regular slider. Again, sliders are disabled until Racemenu and SKSE are ported.

-What’s so special about Beast Race support?-

In Vanilla Skyrim, neither Beast race had a mesh that would allow one eye to be different from the other. This mod comes with some new meshes, provided by expired6978, that separate the beast eyes into left and right, allowing cross-combination of their eye textures. However, this is not without limitation. Argonians and Khajiit still each have different eye meshes, which make them incompatible with other races' textures. While human and elf races will be getting 1,000+ combinations from this mod, Argonians will only get around 575, and Khajiit only about 140, due to the smaller number of available textures. (32 for humans/elves, 24 for Argonians, and only 12 for Khajiit). Again, Beast Race meshes are broken in SSE for now.

-How does it work/What did you do to get these?-

Technical details below. You can skip this paragraph if you don't care about the nitty-gritty details
Using the CK, I found the eye mesh that makes the Left eye different from the Right (in vanilla this mesh is only used to make blind eyes) and created 32 new faceparts using that mesh, one for each of the vanilla non-beast eye textures. Then I copied one of the vanilla eye sets that has a blind eye, and set it to be useable by all non-beast races. I then went over to SSEEdit and duplicated that record 1024 times (32 colors means 32*32=1024). Each set of 32 records was set to use one of the new faceparts I made, and have one of the 32 textures. Then I duplicated all of the records I had made and set them all to the equivalent for the other gender.
A similar process was used for the Beast Races, using the new meshes.
I then went through and unchecked “playable” tag on all vanilla eyes so they don't appear in the slider out of order, and used xEdit to add the playable tag on all my eyes.

-Does this modify any NPCs?-

No. All of the eye combinations are completely new records and are not referenced by anything in the game and will not appear on NPCs. You'll only see them if you put them on your character, or manually edit an NPC.
However, if you are interested in seeing these eyes on your companions, I recommend the mod Familiar Faces. Using that mod, you can turn your own characters into followers for your other characters. Obviously this is pending the SSE release of said mod.

-Compatibility-

This mod should be compatible with about every mod that I can think of. It will use any Texture mod you have, unless they come with their own meshes. Mods that add completely new eye sets will work as they normally do, but will not be Heterochromia-enabled unless I make a patch. (Please note that patches are something I definitely want to do, but given the exponential nature of this mod, it will be slow-going and each subsequent patch will take increasingly large amounts of work. As such, I will only be making patches for eye mods that I personally find interesting and desirable to use. You can suggest eye mods in the comments for a patch and I'll look into it, but I won't guarantee anything.)
Additionally, this will work with custom races, provided that your custom race is compatible with vanilla eye meshes (most custom races are), and provided your race doesn’t automatically assign an eye type (some custom races force you to use vampire eyes, for example)

-Future of the Mod-

• I plan on making "Compatibility Patches" for a some mods that add new eyes so that their new textures will appear in Heterochromia and alongside vanilla colors.
  If you have a recommendation/request, post it in the comments!
• Once SKSE and Racemenu are ported to SSE, I'll reintroduce the 'New Sliders' version, which basically disables the vanilla eye slider and instead supplies a 'Left eye' and 'Right eye' slider, for much easier selection and navigation of the eyes.
  

Planned Patches (Pending Permissions):

• None at the moment.
  

Work-In-Progress Patches

• Hale - Iridum Eye
  

-Installation-

It is strongly recommended that you use NMM, or a similar mod installer. Manual installation is a sure-fire way to mess up your data folder.

-Uninstallation-

Simply deactivate using your mod install software, or delete the .esp if you manually installed it. The .esp for this mod should start with NK.
This mod does NOT add save-changing scripts or mess with any NPCs, so it's safe to uninstall during a savegame, however, it will mess up your character's eyes if you save with one of the new eye sets in place. If you want to uninstall the mod, use the console command "showracemenu" and change your eyes to something not included in the mod first.

-Version History-

• 1.0 - Initial Release. Adds 1024 new eye sets to all non-beast races, in both genders.
• 1.1 - Adds Snow Elf eyes and a second Vampire eye set for an additional 132 eye combinations. Total combinations now at 1,156
  

-Recommended Mods-

• Any eye texture replacer. The better the textures, the prettier this mod's changes become.
  

-Permissions-

Do not upload this mod to any other site. If I want it hosted elsewhere, I will be the one to host it there. I have already uploaded this to Bethnet with console support.
Please ask before using my work in another mod. I would prefer my work to remain in my own hands, but I might make an exception if I like what you propose.
I would prefer if compatibility patches were made only by me, so that the records follow the same formatting, but you DO have my permission to make compatibility patches for other mods without asking. PLEASE give credit where credit is due if you plan on hosting it, and send me a PM about it if you do make a patch so I know that it’s being made.
If I am offline, and don't reply to PM's for more than 3 months, I give my full consent to do anything with this mod that you wish.

-Credits-

expired6978 – For helping me write the RaceMenu script, and for providing new Beast Race eye meshes. These will eventually make their way back into the mod.

Bethesda - For making Skyrim
The xEdit Team - I used their tools heavily during this mod's inception. Without it, my workload would've been increased by a factor of at least 30, and I probably wouldn't have had the patience to do it.
Nexus Mods - For hosting such a great community of modders, and generally being awesome.
The Nexus Mods Community - You guys are the reason I'm doing this, and the reason Skyrim modding is so spectacularly robust.
My mom - You know why.