Install
Three steps to a new sky.
Cornea is a normal Iris shaderpack. If you've installed one before, you already know how.
Install Iris and Sodium
Add Iris and Sodium to your Minecraft 26.x instance. Iris needs Sodium to run, so you need both.
Add Cornea
Drop Cornea Shaders.zip into the shaderpacks folder. Leave it zipped.
Pick a profile
Open Video Settings, then Shader Packs, select Cornea and choose Low, Medium, High or Ultra.
Good to know
A few quick answers.
Do I need a resource pack?
No. Shine, surface detail and glowing ores are built in and work with the default textures.
Is Cornea a version of Photon?
No. Cornea is a separate pack that aims for a similar warm, soft look. Photon is made by SixthSurge, and its screenshots here are only for comparison.
Why are there no sun shadows in the Nether?
The Nether has no sun or moon, so there's nothing to cast them. Lava, fire and glowstone still light the world in colour, and nearby blocks still block that light.
What hardware was it tuned on?
A Ryzen 5 5500 with a 4 GB RX 6500 XT and 16 GB of memory. If you have a slower card, start with the Medium profile and turn up what you miss.
Something looks wrong. What should I send?
A screenshot, the profile you're using, and the Iris error log if the pack fails to load. That's usually enough to find the cause.