Sources & Links:

Artificial Tear Breakdown: http://webeye.ophth.uiowa.edu/eyeforum/tutorials/artificial-tears.htm 

The Best Eye Drops: https://www.reviews.com/eye-drops/ 

Master the Maze of Artificial Tears: https://www.reviewofoptometry.com/article/master-the-maze-of-artificial-tears

Moshirfar M, Pierson K, Hanamaikai K, et al. Artificial tears potpourri: a literature review. Clin Ophthalmol. 2014;8:1419-1433. 

Simmons P, Carlisle C, Shi G, Vehige J. Clinical comparison of lipid-based and aqueous lubricant eye drops. Invest Ophthalmol Vis Sci. 2013;54(15):4329.

Petrolatum Info: https://www.ewg.org/skindeep/ingredient/704786/PETROLATUM/

Natural eye drops: http://www.natoph.com/wp-content/uploads/2014/11/Dry_Eye_Drops_TS.pdf