Preserved Ophthalmic Anti-Allergy Medication in Cumulatively Increasing Risk Factors of Corneal Ectasia

SIMPLE SUMMARY: Allergy is a global health issue, and with the advent of modern medicine comes widely available treatments for allergy symptoms. For the localised treatment of itchiness and inflammation associated with ocular allergies, those affected typically use topical anti-allergy eyedrops. This review sought out previous research to investigate the prevalence of ocular allergy, the contents of anti-allergy medication and the pathophysiology of corneal thinning. We found that benzalkonium chloride, the most common preservative for multiuse eyedroppers, has a documented effect on corneal cell viability, weakening the corneal structure. When compounded by common risk factors for corneal thinning, such as the release of inflammatory enzymes and mechanical pressure applied from rubbing your itching eyes, the cellular damage benzalkonium chloride may inflict on the cornea may further increase the risk of permanent corneal damage. ABSTRACT: The prevalence of allergies is rising every year. For those who suffer from it, ocular inflammation and irritation can be inconvenient and unpleasant. Anti-allergy eyedrops are a readily available treatment for symptoms of ocular allergy (OA) and can help allergy sufferers regain normal function. However, the eye is a delicate organ, and multiuse eyedrops often utilise preservatives to deter microbial growth. Preservatives such as benzalkonium chloride (BAK) have been shown to induce decreased cell viability. Therefore, during a period of high localised inflammation and eye rubbing, it is important that the preservatives used in topical medicines do not contribute to the weakening of the corneal structure. This review explores ocular allergy and the thinning and protrusion of the cornea that is characteristic of the disease keratoconus (KC) and how it relates to a weakened corneal structure. It also describes the use of BAK and its documented effects on the integrity of the cornea. It was found that atopy and eye rubbing are significant risk factors for KC, and BAK can severely decrease the integrity of the corneal structure when compared to other preservatives and preservative-free alternatives.