It comes in a Glasses version and an Earrings version for Teens to Elders, and as an Earrings version for children.
Just like my TS3 version, this is a Head Accessory mesh made from the default eyes, which fits over the sim's underlying eyes. (I also decided to go the extra mile and add a children's version, which my TS3 item didn't have.) So use it if you want to, or don't use it if you prefer the other mod, or you can mix & match them if you want a bit of variety. So, at the time I felt there wasn't a point in releasing mine, but having now dusted mine off and added a few extras to make it more versatile and use it myself, thought I'd upload it anyway in case anyone else might find it useful. This is a conversion of my old TS3 '2 Different Colour Eyes' - I actually converted it a year ago but then discovered that someone in Tumblr-land had already made a heterochromia mod for TS4.