They're just full of shit.

What? Why would the immune system attack the eyes?

Well that's just terrifying

As someone living with an eye injury, this is a deep seated fear.

New phobia unlocked

Yep and if you wear them for too long your body will grow new blood vessels to supply your oxygen-starved eyes with what they need. These new blood vessels can cover your retina and can lead to blindness.

Learned that one by sleeping in daily disposable contacts for a while and losing a significant portion of my peripheral vision.

That's correct. It's generally recommended for lenses to have at least over 100 Dk/t for sleep and they need to be approved for that. Dk/t is the measured oxygen transmission through the lens material, the higher, the better. I would not recommend lenses with Dk/t of 30 and under even for daily wear as they starve eyes of oxygen. Especially since there are very affordable ones with very high Dk/t like Miru and Biofinity (around 160 iirc).

Quit using up all the oxygen.

Eventually, yeah. I had an issue with contacts when I was younger as I have to wear thick toric lenses, which allow very little oxygen through. I would wear them way too long, and I was warned that continuing to do so could cause eventually cause blindness

More like a giant alveolus. But inside out. With a giant sphincter in the middle. That poops light.

Fun fact: your intestines are also lungs. Or maybe more accurately, lungs evolved from intestines. It turns out, you can oxygenate people by sticking an oxygen supply up their ass. Which is a possible treatment for people who have suffered respiratory failure.

Proof that I'm not just blowing hot air up your butt, except maybe I am: https://www.science.org/content/article/mammals-can-breathe-through-their-intestines

He was out of breath.

It is the only part of the body without a blood supply. Instead, it receives nutrients via aqueous humor (the liquid between the cornea and vitreous).

Instead, oxygen dissolves in tears and then diffuses throughout the cornea to keep it healthy.[5] Similarly, nutrients are transported via diffusion from the tear fluid through the outside surface and the aqueous humour through the inside surface.

And because that seemed lacking still and I’m too dumb to figure it out ChatGPT’s response:

The palpebral conjunctival blood vessels and the capillaries of the eyelids supply oxygen to the tear film behind closed lids. Oxygen diffuses from these vessels into the cornea.

You have a high concentration of blood vessels on the inside of your eyelids, which are kept in contact with the cornea by tears. It doesn’t only let oxygen through, some parts of blood (like lymph and antibodies) can also travel through the tears and into your cornea.

My brother sleeps with his eyes party open. He must be eye oxygenmaxxing. Superior eyeballs.

Source?

Tear fluid also provides oxygen