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Dry eye and blepharitis
Dry eye is a multifactorial disease of the ocular surface in which the tear film is unstable and too salty, with inflammation and epithelial damage; most cases come from excess evaporation due to meibomian gland dysfunction, and treatment is stepwise — from artificial tears and lid hygiene to anti-inflammatory drugs and punctal occlusion.
Why it matters in the exam
The tear film has three layers: an outer lipid layer from the meibomian glands that prevents evaporation, an aqueous layer from the lacrimal gland, and a mucin layer from conjunctival goblet cells that allows wetting. So aqueous-deficient dry eye (Sjögren syndrome, anticholinergic drugs, age, LASIK) is distinguished from evaporative dry eye (meibomian gland dysfunction, rosacea, screens and reduced blinking) — and the latter is commoner. Complaints: burning, foreign body sensation, blur that improves with blinking, and paradoxically watering too.
Tests: tear break-up time (TBUT) shorter than 10 seconds, fluorescein or lissamine green staining, the Schirmer test (less than 5 mm in 5 minutes points to severe deficiency), osmolarity and examination of the lid margin. When Sjögren syndrome is suspected — dry mouth, joint pain and SSA and SSB antibodies. Anterior blepharitis — scales around the lashes; Demodex — cylindrical "collarettes" at the base of the lashes. Posterior blepharitis — plugged gland openings and toothpaste-like secretion, often with rosacea.
Treatment is stepwise: artificial tears — preservative-free when used more than 4 times a day; warm compresses, massage and cleaning of the lid margin; addressing environmental factors and drugs. Next step: cyclosporine or lifitegrast drops, a short course of steroid, doxycycline or azithromycin in meibomian disease and rosacea, and punctal plugs. In severe disease — autologous serum and scleral lenses. The DREAM study showed no benefit of omega-3 supplements over placebo.
Key points
- Unstable, salty tear film with surface inflammation.
- Commonest type: evaporative from meibomian gland dysfunction.
- TBUT shorter than 10 seconds; Schirmer below 5 mm.
- Preservative-free tears, compresses, lid hygiene.
- Then: cyclosporine, doxycycline, plugs.
Summary table
| Type | Mechanism | Sign | Treatment |
|---|---|---|---|
| Aqueous-deficient | Low tear production | Low Schirmer, inferior staining | Tears, cyclosporine, plugs |
| Evaporative (MGD) | Deficient lipid layer | Short TBUT, plugged glands | Compresses, hygiene, doxycycline |
| Anterior blepharitis | Staphylococcus, seborrhoea | Scales on the lashes | Lid cleaning, antibiotic ointment |
| Demodex | Mite | Collarettes at the lash base | Dedicated lid cleaning, lotilaner |
| Sjögren syndrome | Lymphocytic gland infiltration | Dry mouth, SSA and SSB | Stepwise treatment and rheumatology work-up |
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Sources
- TFOS DEWS II Report, 2017 — Definition, classification, diagnostic methodology and management
- AAO Preferred Practice Pattern: Dry Eye Syndrome and Blepharitis, 2018 — Evaluation and management
- AAO Basic and Clinical Science Course, Section 8: External Disease and Cornea, 2024-2025 — Ocular surface disease
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.