Visine makes your eyes less red by constricting the blood vessels in your eye. This constriction leads to less blood flow to the various tear glands of the eye, making your eyes dryer and more irritated. It doesn't address why your eye is irritated and in fact makes it worse

I am an ophthalmologist, please don't ask me questions about your specific eyes.

This is a huge concern for our community for a number of reasons. Firstly, the biggest concern here is the lack of quality control. These brands of artificial tears, as far as I know, are not manufactured in the US and are not well known companies.

One of the biggest issues is that artificial tears are over the counter and not paid by insurance (at least in the US). Because of this, people are often going to gravitate towards cheaper products since it's coming out of pocket. Further, there isn't great guidance on which brands to buy (which is why many of my patients tell me they take visine, which is a terrible drop).

Additionally, dry eye is a serious condition (one that I don't focus on in my subspecialty) that can lead to really unfortunate conditions. Firstly, the vast majority of your eyes ability to make clear images (refractive power) comes from your tear film (how well your eye is wet). Having poor tear film (common with aging) can lead to blurry vision.

But even worse, chronic dry eye can lead to scratches on the eye, scarring, or even permanent vision loss. It can make the eye susceptible to infections and at risk for needing a corneal transplant. The vast majority of eyes don't get this bad but it's important to manage it.

The fundamental problem is that treatments like these are not being handled as medical problems, but rather out of pocket expenses. This leads to many brands on the shelf and competing companies and no standardized process to ensure safety.

I won't endorse certain brands but there are many reputable brands that you can find with the help of your local eye specialist.

The bacteria is a form of pseudomonas (one that we had not seen in humans as of yet). Pseudomonas can live in most fluids and cause really violent eye infections that cause damage very quickly.

The two worst contaminants would be pseudomonas and acanthomoeba since they can tolerate extremely hypertonic solutions

You have 6 types of glands that make 3 components of tears:

Lacrimal glands, Krause glands and Wolfring glands make the water part

Zeiss and meibomian make the oil

Goblet cells make the mucous part

They're all important but they get worse as you age. Artifical tears are a great product, but like most medicines can be ruined by the process of producing them. As many comments have mentioned, generics can occasionally be an issue with contamination whereas brand names in the US all have better quality controls.