Topical glaucoma medications - Possible implications on the meibomian glands

One of the most common causes of blindness on a global scale is glaucoma. There is a strong association between glaucoma and increased intraocular pressure (IOP). Because of this, adequate IOP-lowering is the most important treatment strategy, mostly through topical eyedrops. Well-functioning meibomian glands are paramount for maintaining a stable tear film, and their dysfunction is the most common cause of dry eye disease. There is a growing concern that both topical glaucoma medications themselves and their added preservatives damage the meibomian glands, and consequently, the ocular surface. Preserved topical glaucoma medications appear to cause dysfunction and atrophy of the meibomian glands. Upon comparison, preserved formulations caused more symptoms of dry eye, tear film instability, inflammatory changes and meibomian gland dropout than the preservative-free counterpart. However, although seemingly less detrimental, unpreserved alternatives may diminish glandular efficacy, and, depending on the active ingredient, lead to glandular death. This negatively impacts quality of life, adherence to treatment regimens and prognosis. In this review, we explore the available evidence regarding the effects of IOP-lowering eye drops on the meibomian glands.