Eye upgrades alter the eyes, whether it be the colour, pupils, or even adding another eye. Any upgrade that alters the pupils obviously requires the pupil upgrade first. Please note there is no upgrade that changes your Mormorian's base eye colour, Gradient Eyes, Iris Rings, and Heterochromia add a colour, but it will never completely change the original colour. There is an item in the shop that allows you to change their eye colour completely.
Pupils
Seeing the world with new eyes! EXP Needed: 10 Requirements: Draw your Mormorian with a background, background must have some depth!
Coloured Pupils
Probably not colour blind EXP Needed: 15 Requirements: Must have Pupils upgrade, cannot be used to make them look blind
Slit Pupils
Like a cat or reptile EXP Needed: 70 Requirements: Draw them with a night-time background, must have Pupils upgrade
Shaped Pupils
Want actual heart-eyes? Now you can! EXP Needed: 90 Requirements: Must have Pupils upgrade
Coloured Sclera
The sclera no longer has to be white! EXP Needed: 110 Requirements: Draw them getting something in their eyes
Glowing Eyes
Shine bright EXP Needed: 180 Requirements: Animate your Mormorian glowing in some way! (Can be the eyes glowing)
Gradient Eyes
Two-toned eyes blended together EXP Needed: 240 Requirements: Draw your Mormorian admiring something
Iris Rings
Rings of extra colour around the pupils! EXP Needed: 350 Requirements: Must have Pupils upgrade
Heterochromia
Can be sectoral or full EXP Needed: 350 Requirements: Draw them looking up at the sky
Third Eye
Your third eye has been opened EXP Needed: 500 Requirements: Must be at least 3 months old and know 3 basic magic types