Chronic Dry Eye Disease

The vicious cycle

The tear film has three components: an oil layer from the meibomian glands that stops evaporation, a watery layer from the lacrimal gland, and a mucin layer that spreads it. When any fails, the film breaks up too soon, the surface dries between blinks, and the exposed cells release inflammatory signals. Inflammation in turn damages the glands and the surface further, and the tears become more concentrated, which is itself irritating. Once established, the cycle sustains itself, which is what makes dry eye chronic.

Symptoms

Grittiness, burning, stinging, a feeling of something in the eye, redness, tired eyes, light sensitivity, and vision that blurs and clears with blinking. Paradoxically, watering: a dry surface triggers reflex tears that are watery and do not stay. Symptoms are usually worse later in the day, in air conditioning, on screens, in wind, and on waking if the lids do not close fully. Contact lenses become uncomfortable.

Causes and risk factors

• Meibomian gland dysfunction, present in most chronic dry eye
• Blepharitis and ocular rosacea affecting the lid margins
• Reduced blinking during screen use
• Age, and hormonal change at menopause
• Medications: antihistamines, antidepressants, blood pressure drugs, isotretinoin, and preserved eye drops used long term
• Autoimmune conditions: Sjogren's syndrome, rheumatoid arthritis, lupus, thyroid eye disease
• Contact lens wear and previous laser eye surgery
• Environment: dry climates, air conditioning, wind, smoke

Diagnosis

A dry eye evaluation measures the tear film, images the glands, tests for inflammation and examines the lids, and categorizes the disease by cause and severity. This is what distinguishes chronic dry eye from the occasional dryness everyone experiences, and it is what directs treatment.

Treatment that breaks the cycle

Two things have to happen: the tear film has to be stabilized, and the inflammation has to be brought down. Stabilizing the film means restoring the oil layer with meibomian gland treatment, lid hygiene, warm compresses, and omega-3 supplementation; supplementing volume with preservative-free lubricants and, where production is low, punctal plugs. Reducing inflammation means prescription drops such as cyclosporine or lifitegrast, short courses of steroid, and, for rosacea, oral doxycycline or intense pulsed light. Severe disease adds autologous serum tears and scleral lenses. Treatment is stepwise and measured, and progress is typically assessed over two to three months.