I call BS on both the salt and deicer. I'm gonna knock 'em, and I'm not gonna try 'em.
How would you like for someone to do that to you - even without a corneal ulceration?
That ranks right up there with smearing coal tar on a dog's head to cure 'the distemper', with regard to the likelihood of them being an effective treatment. It's BS; pure and unadulterated. I guess some old spouse's tales just won't die.
If you've used these 'treatments' and your cows recovered uneventfully, I can assure you that they did so IN SPITE of you throwing/squirting this stuff into their eyes.
Your physician/ophthalmologist won't be throwing salt or squirting an alcohol solution in your eye if you have a corneal ulcer - why would any thinking person think that doing so to a cow would improve the situation?
Anything you spray or introduce into an animal's eye will be washed out in no less than 10 minutes due to normal tear action - and even more rapidly when there's a condition present that causes increased tearing - like pinkeye. So...even spraying nitrofurazone powder, or squirting mastitis treatment tubes into the eye, has a very very temporary effect.
I have some serious doubts about whether the subconjunctival penicillin injections they taught us to do in veterinary school really do anything once the needle hole seals and the penicillin stops leaking out. I quit doing those 20 years ago.
Best treatment is accomplished by using one of the long-acting tetracycline or other broad-spectrum systemic antimicrobial products that reach effective treatment levels in the tears, so that they eye is constantly bathed with an effective concentration of antibiotic.
I have sewn the third eyelid up to the upper lid to provide additional protection to severely ulcerated corneas, but haven't reviewed recent literature to determine whether or not that really helps or not.