The problem there isn't your receptors, which are UV sensitive. The problem is your lens, which filters it out. Remove the lens and you can see UV just fine.

Until you get eyeball cancer, that is. UV is mutagenic. That's why you filter it out.

People with cataracts get replacement lenses, and some exist that don't filter the UV. I think they're hard to get, what with the whole "eyeball cancer" thing. But if I get to my 70s and need replacement lenses (I do have a family history), I'm going to campaign to see if I can spend a couple of decades looking at the pretty birdies.

It's not just cancer right? UV light will damage those sensitive photoreceptor cells, so you would end up seeing less and less of anything over those couple of decades. Even non-UV blue light is hard for the eyes to deal with. Personally I'd just prefer wearing glasses that shift the UV to some other part of the spectrum.

> Personally I'd just prefer wearing glasses that shift the UV to some other part of the spectrum.

Does this exist? I thought those kinds of non-linear effects only happen at extremely high fields (e.g. with a very fast pulsed laser to concentrate energy in time)

No, at least not without active electronics.

Fluorescence?

Going to reply to myself since I searched for it on a whim.. https://www.sumita-opt.co.jp/en/products/lumilass.html

Are you eyes more sensitive to UV than the rest of your body?

I guess melanin absorbs UV in the skin, so this serves a similar purpose in the eye?

I'm not sure about more sensitive, but I know the immune system (which cleans up a lot of pre-cancerous cells before they become a problem) is much less active in the eyeball, so it probably pays to have extra defense against cell damage.

"Sensitivity to light" is the primary function of the eye.

This implies that birds don’t get eye cancer even though their lenses are different. I wonder what their protection is

At a guess: they don't live long enough for it to outweigh the benefits. While there are exceptions, wild birds often live only a few years.