Dry eye and Glaucoma
Dry eye and glaucoma occur in 50-60% of patients. The main reason for this is that glaucoma drops contain benzalkonium chloride, a preservative, which acts as a soap. This soap can cause chronic irritation and inflammation of the cornea and conjunctiva.
Dry eye syndrome occurs in 1 in 3 patients over the age of 65 and is commoner in women. Dry eye itself causes inflammation so patients on preservative containing drops have an exacerbation of their symptoms. Using preservative free drops can alleviate some of the symptoms. A large bleb after filtering glaucoma surgery can also alter the lids contact with the eye and amplify symptoms.
Risk factors for the development of dry eye include the following:
- Mebomium gland dysfunction which causes a lack of oily tears and evaporative dry eye
• Age – Tear production declines with age and the lids become less effective at spreading tears over the ocular surface
• Excessive screen time – when we read, we blink less often. This causes evaporation of tears.
• Medications – Antidepressants, the oral contraceptive and antihistamines reduce tear production
• Air conditioning and reduced humidity can exacerbate symptoms
• Autoimmune diseases like Rheumatoid arthritis, Sjogrens syndrome and Lupus
• Long term contact lens wear, laser eye surgery and cosmetic lid surgery
The treatment of dry eye syndrome is centred on either aqueous deficiency or evaporative dry eye. Patients with dry eye often have a combination of both, so the approach to treatment is often multifaceted.
The mainstay of treatment is tear replacement. There are a vast number of over the counter medications available. Preservative free lubricants should be used in those patients requiring drops more than four times a day and in contact lens wearers. Expressing the meibomium glands with hot eyelid massage can the reduce the frequency of the lubricant that is used. Ciclosporin drops and steroid drops are prescribed to reduce inflammation. Preventing drainage of tears with punctal plugs is often helpful and is associated with a further reduction in intraocular pressure. In severe cases that do not respond to the above treatment the patient’s own serum can be used as drops.
In meibomium gland dysfunction, microbiological changes are associated with an increased melting point of the oil they produce. This leads to blockage of the glands.
Lifestyle factors associated with MGD include stress, lack of sleep, alcohol and spicy food.
Omega 3 supplements are thought to improve meibomium gland dysfunction. Certain types of glaucoma drops are more likely to be associated with MGD. Hot compresses, manually removing debris with lid cleansers and avoiding make-up can improve symptoms. If severe, a course of doxycycline is often prescribed.