Table 3: Types of dose containers based on units and use of preservatives².

Type	Feature	Limitation	Implication(s)
Multidose artificial lubricants with preservatives	Economic versus unit dose	Contains preservatives	Greater risk of adverse changes to the ocular surface and toxicity
Dispensers with unidirectional valves	Multidose bottles yet preservative-free	Expensive Availability issues	Lesser risk of adverse events May be less commonly used
Unit dose, preservative-free	Absence of preservatives	Expensive More difficult for less dextrous individuals to open	Lesser risk of adverse changes to the ocular surface and toxicity
Disappearing preservatives containing multiple dose drops: Oxidative preservatives Sodium chlorite Sodium perborate Polyquaternium-1	Sodium chlorite decomposes into chloride ions and water when exposed to UV light after instillation, and sodium perborate decomposes into water and oxygen in contact with the tear film	May have negative effects on the ocular surface	Avoid issues with long-term exposure to preservatives Lower impact on the ocular surface

UV = ultraviolet.