Although all eye drops for dry eye may appear similar, they contain different ingredients in various concentrations. However, most are made up of similar categories of ingredients that coat the eye to keep it moist and lubricated to decrease burning, irritation and discomfort, according to drug manufacturer Allergan. Most dry eye drops contain a hydrogel, which increases the amount of time the drop remains on the eye. Some contain a preservative, and one contains anti-inflammatory ingredients. People may have better results with one type than another.
Hydrogels
Hydrogels are the active ingredients used to make most dry eye drops viscous so that they stay on the eye longer and keep tears in the eye longer, according to the University of Illinois Eye and Ear Infirmary. Commonly used hydrogels include hydroxypropyl methylcellulose (HPMC), carboxy methylcellulose (CMC), polyvinyl alcohol (PVA), carbopol, polyvinyl pyrrolidone, polyethylene glycol, dextran, hyaluronic acid or Carbomer 940 (polyacrylic acid). HP-Guar, used in Systane drops, forms a gel layer in the eye that increases viscosity. Very high viscosity tears last longer on the eye but may cause blurry vision that lasts for 13 to 24 minutes, according to the Eye and Ear Infirmary.
Oils
Drops that contain oil help dry eye caused by a lack of lipids in the tear film that covers the eye, according to the Eye and Ear Infirmary.
Preservatives
Because eye drops for dry eyes are packaged in multi-use vials, many brands include preservatives. The Eye and Ear Infirmary says some types of preservatives are more damaging to eyes than others. Two commonly used preservatives are benzalkonium chloride (BAK), which can irritate the eye and shouldn't be used more than four times a day, and chlorobutanol. Newer types of preservatives, such as Purite, GenAua or Polyquad, cause less irritation to the eye. Eye drops without preservatives are usually packaged in single-dose vials.
Anti-Inflammatory Drug
An anti-inflammatory prescription drug, Restasis, is used to treat dry eye caused by inflammation, with redness and irritation. Restasis contains cyclosporine, a drug that decreases cells that cause inflammation such as white blood cells. Corticosteroid eye drops may also be used to treat some types of dry eye, according to William Townsend, O.D., in the October 2007 issue of Optometric Management.
