Lubricant eye gels are water-soluble and available as very thick drops in preservative-free single-use vials (Ivizia Severe, Refresh Celluvisc) or as thicker gels in a tube with a mild "dissipating" preservative (Genteal Gel, Systane Gel - both of which have been subject to frequent backorders and shortages).
Lubricating eye ointments are made from a petrolatum and mineral oil base, sometimes with added ingredients. Like the gels that come in tubes, most of these ointments have been subject to periodic shortages. However, we do not recommend substituting generic eye ointments or unregulated imports because of longstanding issues with poor quality contract manufacturing and recalls due to contamination.