Vegan Vegetarian Dry Eye Supplements
I was asked a great question in clinic recently about the effectiveness of Omega 3 sources that are not fish based i.e. Vegan Omega 3 options and Flax Seed. (Most all brands of Omega 3 source are fish such as PRN Omega 3 or Nutrasea Dry Eye Formula or I-VU)
From clinical experience, folks never seemed to have much success for vegetarian dry eye treatment with flax seed Omega 3 based supplements or flax seed use. I did not know exactly why but a great podcast from Dr. Peter Attia clarified the answer (reference below).

Vegetarian Dry Eye Treatment limitations
Although flax seed does indeed have Omega 3, its form is 'ALA'. Our bodies can not use ALA directly and the conversion from ALA to our usable forms (EPA & DHA) is simply not very efficient. Massive amounts of ALA would be required to approach the large doses of EPA / DHA that I commonly recommend for dry eye treatment.
There is one vegan source derived from algae that does have EPA and DHA (no conversion required). mEYEspa sells NutraVege Plant Based Omega 3. This Vegetarian Dry Eye treatment works great because it is the required form of Omega-3 Fatty Acids (EPA & DHA)! The costs are a bit higher for this source of Omega-3 but it is a great alternative for those with dietary limitations.
Remember that Omega-3 dosing for Dry Eye treatment for most folks should be:
EPA + DHA = ~1200mg daily. Three (3) of the NutraVege softgels provides this minimum dose.
Reference: The Drive Podcast - Dr Peter Attia December 9, 2019
#83 – Bill Harris, Ph.D.: Omega-3 fatty acids