Dry Eye Disease (Keratoconjunctivitis Sicca)
Ophthalmology: Surface and Lacrimal Disorders
1. Pathophysiological Mechanisms
Dry eye is multifactorial, generally categorized into two main subtypes:
- Aqueous-Deficient: Reduced tear production (e.g., Sjögren syndrome, lacrimal gland obstruction).
- Evaporative: Increased tear loss, most commonly due to Meibomian Gland Dysfunction (MGD), resulting in poor lipid layer quality.
2. Clinical Assessment
| Diagnostic Test | Clinical Significance |
|---|---|
| Schirmer Test | Measures total tear production over 5 minutes; < 10 mm is typically suggestive of aqueous deficiency. |
| Tear Break-Up Time (TBUT) | Measures stability of the tear film; < 10 seconds is abnormal (suggests evaporative DED). |
| Vital Dye Staining | Fluorescein or Lissamine Green stains damaged corneal/conjunctival epithelium. |
3. Management & High-Yield Pearls
- First-Line: Preservative-free artificial tears and eyelid hygiene (warm compresses/lid scrubs) for MGD.
- Second-Line: Anti-inflammatories (topical cyclosporine or lifitegrast) and punctal plugs.
- Systemic Association: Always keep Sjögren syndrome (dry eyes + dry mouth) in the differential for severe cases.
- Educational Resource: For detailed management algorithms, ocular surface diagrams, and clinical practice questions, visit mymedschool.org.