Tip of the Month
Publishing date: December 2013
The Science behind the Tip
Many glaucoma drops contain a preservative agent to minimise the risk of microbial contamination. Benzalconium chloride, a cationic surfactant, is the most widely used preservative, but even in doses of 0.002% to 0.004% can result in toxic effects on the surface of the eye and ocular inflammation. (1)
Symptoms and signs of ocular surface disease (OSD) are found in 48-60% of patients on topical glaucoma medication (2) (3). This is a multifactorial condition which leads to adverse local reactions, reduced visual acuity, reduced quality of life and reduced compliance with prescribed therapy. (1). Risk factors associated with OSD include the number of preserved drops used and duration of therapy. (4) An improvement of symptoms is found if these patients are switched to preservative-free topical medication. (1)
Contributor: Frances Meier-Gibbons, Switzerland
1. Baudouin C, Labbé A, Liang H et al Preservatives in eyedrops: the good, the bad and the ugly. Prog Retin Eye Res 2010; 29 (4) 312-334.
2. Leung EW, Medeiros FA, Weinreb RN. Prevalance of ocular surface disease in glaucoma patients. J Glaucoma 2008; 17 (5) 350-355.
3. Fechtner RD, Godfrey DG, Budenz D et al. Prevalence of ocular surface complaints in patients with glaucoma using topical intraocular pressure lowering medications. Cornea 2010; 29: 618-621.
4. Rossi GC, Pasinetti GM, Scudeller L et al. Risk factors to develop ocular surface disease in treated glaucoma or ocular hypertension patients. Eur J Ophthalmol 2013; 23 (3) 296-302.
Tip Reviewer: Roger Hitchings
Tip Editors: John Salmon and John Thygesen