Glaucoma therapy and dry eye

Patients with glaucoma have increased prevalence of dry eye (DE) compared to age-matched population without glaucoma. Clinical presentation of DE varies among individuals and may significantly reduce quality of life. The onset and deterioration of DE is caused by the toxic-inflammatory effects of preservatives in eye drops, active substance itself, and added, pharmacologically inactive substances or excipients. Ocular surface changes most frequently include superficial punctate keratitis, tear film instability, and allergic reactions. Despite the lack of symptoms, clinical signs may indicate ocular surface damage. Discordance between signs and symptoms is partly caused by decreased corneal sensitivity induced by neurotoxicity of the preservative benzalkonium chloride (BAK). Therefore, it is important to evaluate ocular surface before initiating glaucoma therapy and during follow-up also in asymptomatic patients. Preservative-free and/or BAK-free therapy is indicated in patients with severe DE and allergy to preservatives, and recommended in patients with DE of moderate severity, blepharitis, in symptomatic patients, before filtering surgery to reduce preoperative inflammation, in those with moderate fluorescein staining of grade 2 on Oxford scheme, and reduced tear film break-up time.