This educational supplement is sponsored by Allergan Global Medical Affairs.

Years ago, I presented alongside Jeffrey Gilbard, MD, who believed that too many preservatives were “pickling” the ocular surface. There have now been numerous investigations into frequent use of preserved ocular drops, finding that frequent use of preserved drops caused changes in the ocular surface structure.^1-3 This has led to the understanding that, if a patient is putting any preserved drop on his or her eye more than four times per day, the cumulative preservative load is going to cause problems.

This growing understanding has led to the development of alternatives such as transiently preserved and preservative-free formulations. Transient preservatives such as sodium chlorite, sodium perchlorate, and sorbitol are transformed into water and oxygen by the shear force of a blink. New packaging technologies have enabled preservative-free formulations that avoid any preservative load on the eye. Whenever a patient is using a cumulative of four or more drops, it is optimal to switch them to nonpreserved alternatives.

1. Gasset AR. Benzalkonium chloride toxicity to the human cornea. Am J Ophthalmol. 1977;84(2):169–171.

2. Chung SH, Lee SK, Cristol SM, et al. Impact of short-term exposure of commercial eye drops preserved with benzalkonium chloride on precorneal mucin. Mol Vis. 2006;12:415-421.

3. Noecker R. Ophthalmic preservatives: considerations for long-term use in patients with dry eye or glaucoma. Rev Ophthalmol. 2001;8(6):73–79.