Dry Eye Disease

Dry eye disease is a multifactorial disease of the ocular surface characterised by loss of tear film homeostasis, with tear instability, hyperosmolarity, inflammation, and neurosensory abnormalities leading to symptoms and surface damage.

• Types:
  • Aqueous deficient: reduced lacrimal secretion from Sjögren syndrome (primary and secondary), non-Sjögren causes (age related lacrimal gland atrophy, sarcoidosis, lymphoma, radiation, graft versus host disease, HIV, hepatitis C), and reflex block (contact lens, diabetes, neurotrophic cornea, refractive surgery).
  • Evaporative: meibomian gland dysfunction (the commonest cause), blink abnormalities (screen use, Parkinson disease), lagophthalmos, and ocular surface disease.
  • Mixed, which is the usual real world picture.
• Risk factors: age, female sex (menopause and androgen deficiency), contact lenses, screens, low humidity, topical preserved drops, systemic drugs (antihistamines, antidepressants, isotretinoin, diuretics, beta blockers, anticholinergics), vitamin A deficiency, and rheumatic disease.

• Dryness, burning, grittiness, foreign body sensation, redness, photophobia, fluctuating vision, and contact lens intolerance; paradoxical tearing (reflex).
• Symptoms worsen in the evening, with screen use, wind, and air conditioning.
• Signs: reduced tear meniscus, debris in tear film, interpalpebral conjunctival and corneal staining, filaments, and blepharitis with meibomian gland capping or foamy tears.
• Severe disease: corneal epithelial defects, thinning, infection, scarring, and neovascularisation.

• Symptom score (standardised questionnaires such as the Ocular Surface Disease Index).
• Tear film break up time (below 10 seconds is abnormal); Schirmer test without anaesthesia (below 5 mm in 5 minutes is severe aqueous deficiency, below 10 mm borderline); fluorescein staining of cornea and lissamine green staining of conjunctiva; tear osmolarity (above 308 mOsm/L or inter eye difference above 8 mOsm/L); tear lactoferrin and MMP-9 point-of-care tests; meibography and lipid layer imaging.
• Evaluate meibomian gland expressibility and quality, lid margin, and blink.
• Systemic workup in aqueous deficiency with extraglandular features: ANA, anti-Ro (SSA), anti-La (SSB), rheumatoid factor, immunoglobulins, and salivary gland assessment; exclude drug causes.
• Differential diagnosis: allergic conjunctivitis, infectious conjunctivitis, neurotrophic keratopathy, and toxic keratopathy.

• Stepwise by severity:
  • Step 1: education, remove aggravating drugs, increase blinking and take screen breaks (20-20-20), humidify the room, avoid direct airflow, stop smoking, review contact lens wear, treat allergy and blepharitis, oral omega-3 fatty acids (1000 mg to 2000 mg daily; evidence is mixed), preservative free artificial tears 4 to 6 times daily (carboxymethylcellulose 0.5 to 1 percent, hyaluronate 0.1 to 0.3 percent, or hydroxypropyl guar) and gel or ointment at bedtime (use preservative free formulations when instilled more than four times daily).
  • Meibomian gland dysfunction: warm compress 10 minutes daily to twice daily with gentle lid massage and lid margin cleaning, in office thermal pulsation or intense pulsed light, and perfluorohexyloctane drops four times daily for evaporative disease.
  • Step 2: topical ciclosporin 0.05 percent twice daily (or 0.09 percent twice daily, or 0.1 percent once daily) for 3 to 6 months before full effect; lifitegrast 5 percent twice daily; short course topical corticosteroid (fluorometholone 0.1 percent or loteprednol 0.25 percent four times daily for 2 to 4 weeks, then taper) for flares; punctal plugs (collagen or silicone) or cautery for aqueous deficiency; topical azithromycin 1 percent daily and oral doxycycline 50 mg to 100 mg daily for 3 months (or azithromycin 500 mg daily for 3 days monthly) in meibomian gland disease; varenicline nasal spray 0.03 mg per spray one spray in each nostril twice daily.
  • Step 3: autologous serum eye drops 20 to 50 percent four to six times daily, scleral contact lenses, and moisture chamber goggles.
  • Step 4: amniotic membrane (self-retaining ring or surgical), systemic immunosuppression for Sjögren related disease, permanent punctal occlusion, salivary gland autotransplantation, and tarsorrhaphy.
• Systemic secretagogues in Sjögren syndrome with dry mouth: pilocarpine 5 mg orally four times daily or cevimeline 30 mg orally three times daily (sweating, cholinergic effects; avoid in asthma and narrow angle glaucoma); hydroxychloroquine 200 mg to 400 mg daily for arthralgia; systemic therapy for extraglandular disease.
• Treat contributing disease: blepharitis, lagophthalmos (tape, tarsorrhaphy, gold weight), floppy eyelid, thyroid eye disease.
• Follow up every 3 to 6 months; severe disease monthly. Monitor for corneal infection and ulceration.
• Complications: punctate keratopathy, filamentary keratitis, ulceration and perforation, infectious keratitis, scarring, and chronic pain with neuropathic ocular pain.