Dry eyes

Dry Eyes (Keratoconjunctivitis Sicca)

Introduction

Dry eye disease (DED) is a multifactorial disorder of the tears and ocular surface, leading to symptoms of discomfort, visual disturbance, and tear film instability. It is caused by reduced tear production or excessive tear evaporation, resulting in inflammation and damage to the ocular surface.

Globally, it affects up to 10–30% of adults, more common in women and the elderly. Beyond discomfort, it significantly impacts quality of life, work productivity, and ocular health.

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Normal Tear Film

The tear film has three essential layers:

1. Lipid layer (outer): Secreted by meibomian glands, prevents evaporation.

2. Aqueous layer (middle): Secreted by lacrimal glands, provides moisture and nutrients.

3. Mucin layer (inner): From conjunctival goblet cells, stabilizes tear film and spreads evenly.

Deficiency in any layer → instability → dry eye symptoms.

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Classification of Dry Eyes

1. Aqueous-deficient dry eye: Reduced lacrimal secretion (e.g., Sjögren’s syndrome).

2. Evaporative dry eye: Excessive evaporation (meibomian gland dysfunction, eyelid disease).

3. Mixed forms: Most common.

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Causes of Dry Eyes

1. Environmental and Lifestyle Factors

• Air conditioning, low humidity, wind, prolonged screen time (reduced blinking).

• Contact lens use.

• Smoking, alcohol.

2. Age and Hormonal Changes

• Aging reduces lacrimal secretion.

• Menopause: reduced estrogen/androgen → meibomian gland dysfunction.

3. Medications

• Antihistamines, antidepressants (SSRIs, TCAs), anticholinergics.

• Beta-blockers, diuretics, isotretinoin.

• Chemotherapy agents.

4. Systemic Diseases

• Sjögren’s syndrome (autoimmune destruction of lacrimal/salivary glands).

• Rheumatoid arthritis, lupus, scleroderma.

• Diabetes mellitus.

• Thyroid disease (exophthalmos with incomplete lid closure).

• Parkinson’s disease (reduced blinking).

5. Ocular Conditions

• Meibomian gland dysfunction (common cause of evaporative dry eye).

• Blepharitis.

• Vitamin A deficiency (rare in developed countries).

• Ocular surgery (LASIK, cataract surgery).

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Clinical Features

• Foreign body sensation, gritty or sandy feeling.

• Burning, stinging, itching.

• Redness, eye fatigue.

• Blurred or fluctuating vision (worse with prolonged visual tasks).

• Reflex tearing (paradoxical watering due to irritation).

• Difficulty wearing contact lenses.

• In severe cases: photophobia, corneal ulcers, impaired vision.

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Diagnostic Approach

1. History

• Symptom severity, environmental triggers.

• Medication and systemic disease history.

• Duration, diurnal variation.

2. Examination

• Inspection: conjunctival redness, reduced tear meniscus.

• Eyelid margin disease (blepharitis, meibomian gland dysfunction).

3. Clinical Tests

• Schirmer’s test: Filter paper strip in lower eyelid; <5 mm wetting in 5 min = low tear production.

• Tear breakup time (TBUT): <10 sec indicates tear film instability.

• Fluorescein/lissamine green staining: Shows corneal epithelial damage.

• Osmolarity testing: Hyperosmolar tears = dry eye.

4. Laboratory (if systemic disease suspected)

• ANA, anti-Ro/SSA, anti-La/SSB antibodies (Sjögren’s).

• Blood glucose, thyroid function tests.

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Management and Treatment

Treatment aims to relieve symptoms, improve tear film stability, and prevent complications.

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A. General and Lifestyle Measures

• Frequent breaks during screen time (20-20-20 rule).

• Adequate hydration.

• Avoid smoke, wind, air conditioning.

• Humidifiers in home/workplace.

• Sunglasses outdoors to reduce evaporation.

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B. Pharmacological Therapy

1. Artificial Tears (First-Line)

• Carboxymethylcellulose, hydroxypropyl methylcellulose, polyethylene glycol.

• Use preservative-free drops for frequent application (every 1–2 hours if needed).

• Lubricating gels/ointments at bedtime for severe dryness.

2. Anti-inflammatory Agents (for moderate-to-severe cases)

• Topical cyclosporine 0.05% (Restasis, generic available): 1 drop in each eye twice daily.

• Lifitegrast 5% ophthalmic solution: 1 drop in each eye twice daily.

• Topical corticosteroids (short-term for flares):

  • Fluorometholone 0.1% or loteprednol 0.2%, 1 drop 2–4 times daily for 2–4 weeks.

3. Secretagogues (stimulate tear production)

• Pilocarpine: 5 mg orally three times daily.

• Cevimeline: 30 mg orally three times daily (especially in Sjögren’s syndrome).

4. Vitamin A Supplementation (if deficient)

• Vitamin A (retinol): 10,000–25,000 IU orally daily (or parenteral in severe deficiency).

5. Antibiotics (if meibomian gland dysfunction/blepharitis)

• Topical azithromycin 1% drops: 1 drop twice daily for 2 days, then once daily for 12 days.

• Oral doxycycline: 50–100 mg orally daily for 1–2 months (low-dose anti-inflammatory effect).

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C. Non-Pharmacological / Procedural Options

• Punctal plugs: Occlusion of tear drainage ducts to retain tears.

• Thermal pulsation devices: Improve meibomian gland function.

• Autologous serum eye drops: For severe, refractory cases.

• Scleral contact lenses: Provide continuous lubrication for severe ocular surface disease.

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Complications

• Chronic conjunctivitis.

• Recurrent corneal erosions.

• Corneal ulceration and scarring → vision loss.

• Secondary infections.

• Reduced quality of life and productivity.

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Prognosis

• Mild/moderate dry eye: Good prognosis with lifestyle changes and artificial tears.

• Severe cases (Sjögren’s, post-radiation, autoimmune): Chronic, but symptoms manageable with advanced therapy.

• Untreated: Risk of irreversible corneal damage and vision impairment.

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Patient Education

• Dry eye is often chronic and requires ongoing care.

• Use preservative-free artificial tears if frequent use is needed.

• Follow dosing instructions for medications like cyclosporine or corticosteroids.

• Report worsening pain, vision loss, or photophobia urgently.

• Maintain good eyelid hygiene if blepharitis present.