Glaucoma-Ocular surface disease-Eye drops-Preservatives: an overview

Background Research over several decades revealed that preservatives in eye drops lead to toxic changes of the ocular surface (conjunctiva, cornea) that can penetrate into the anterior chamber and change the structure of the trabecular meshwork. Ocular surface diseases and glaucoma are chronic diseases which usually need a lifelong topical treatment. The aim of this article is to give an overview about the status of preservative and preservative-free topical intraocular pressure lowering eye drops. Material and methods Some of the numerous publications dealing with this topic were summarized. Results There is plenty of evidence that preservatives in eye drops negatively affect ocular tissues. Many of the patients with glaucoma suffer from ocular surface disease. Subjective symptoms and objective signs occur more frequently or get worse with time and topical treatment. These include pricking, burning, itching, foreign body sensation, dry eye as well as blepharitis, Meibomitis, decrease of mucin in tears, positive fluorescein staining, keratitis filiformis and as worst case the formation of a pseudopemphigoid. Allergy, toxicity, sensitivity, and intolerance cannot be clearly distinguished due to complex mechanisms. Not all of the glaucoma patients need preservative-free eye drops but many of them may profit of a change to these. Specific questionnaires and disease-targeted examinations help to determine patients at high risk, who will profit when starting with a preservative-free treatment. Conclusion Patients at risk need a preservative-free topical treatment from the beginning. Careful questioning and examination will help to find these patients and to treat them properly. In cases of subjective complaints and objective signs of ocular surface disease, a change from preservative to preservative-free eye drops seems to be very recommendable.