Which Type of Artificial Tears is Right for Me?

 

There are five artificial tears that provide ocular surface moisture to those with dry eye. Each artificial tear has its own unique properties and is available as an over-the-counter or prescription medication (Table 1). A patient considering artificial tears should consult his or her doctor for a diagnosis of dry eyes and for recommendations regarding which artificial tears might be appropriate. Patient characteristics such as severity of dryness, level of comfort desired, and types of activities in which he or she participates will help guide the choice between formulations. Artificial tears may be used at any time during the day depending on symptomology and levels of dryness.

The first artificial tear was made publicly available in 1976 after being approved by the FDA. Since then, more than 30 different artificial tears have been marketed in the United States.

All artificial tears are regulated by the FDA as OTC drugs. Each artificial tear must follow stringent quality control measures during manufacturing to ensure that there is no contamination and that concentrations of active ingredients are within required limits. All artificial tears contain some or all of these three basic components: an osmotic agent, a solvent system, and an artificial wetting agent.

 

A schematic representation of typical artificial tear formulations. These basic ingredients make up the artificial tear solutions. Image used with permission from Dr Kirkman Laboratories' presentation , provided on their website here .

Osmotic Agent

An osmotic agent is used to pull water into the eye through increased osmotic pressure. This artificial tear ingredient is usually a carbohydrate or a cellulose polymer, which work synergistically either by being hyperosmolar (pulling water into the eye), iso-osmolar (keeping water in the eye), or hypo-osmolar (drying out the surface of the eye) depending on their concentrations. Hyperosmolar artificial tears are most commonly used to treat mild symptoms associated with dry eyes. Iso-osmolar artificial tears can be used at any symptom level and for extended wear lenses when more moisture is needed in the form of film over the cornea. Hypo-osmolar artificial tears are usually reserved for moderate to severe symptoms where higher levels of tear film osmotic pressure are needed to keep artificial tear volume constant on the ocular surface.