If you do a google search on "fish oil and dry eyes" you can get more info.
Noticed someone mentioned to be sure and use a good brand. I'm not sure which one's are considered good. I use "Nature Made" brand. Am able to get it at the drugstores and also the pharmacy at Cub Food.
In addition to fish oil, someone spoke of "krill oil"; believe they said they found it even better than fish oil. (Have never used krill oil, so can't speak for that.)