Preservative Related Ocular Surface Toxicity and the Need for Preservative Free Eye Drops in Ocular Surface Disorders - Recommendations of an Expert Group.

Preservatives are commonly used in eye drops to maintain sterility, to prolong shelf life and to enhance penetration into the eye. Cell culture and animal studies have demonstrated that commonly used preservatives have severe toxic effects on meibomian gland epithelial cells, conjunctival epithelial cells and corneal epithelial cells. Some preservatives penetrate into deeper tissues and cause inflammatory damage to the eye. Clinical studies show that symptoms and signs of ocular surface disease are much more common in patients using preserved eye drops. The beneficial effect of switching patients from preserved to preservative free eye drops has also been demonstrated in many studies. Preservative free eye drops are not universally available, especially in multi-dose vials, and may be more expensive than preserved eye drops. Awareness amongst physicians and patients about the potentially severe adverse effects of preserved eye drops is lacking. This article summarizes the laboratory and clinical evidence on this topic, and lists the recommendations of an expert group for various stakeholders.