Dry Eye Disease

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Introduction & Tear Film - Tear Trouble

  • Dry Eye Disease (DED): Multifactorial; loss of tear film homeostasis, symptoms of discomfort, visual disturbance, tear film instability, potential ocular surface damage.
  • Tear Film (3 layers):
    • Lipid (Outer): Meibomian glands; prevents evaporation, maintains surface tension.
    • Aqueous (Middle): Lacrimal glands; oxygen, nutrients, antimicrobials.
    • Mucin (Inner): Goblet cells; corneal wettability, adherence. Tear film layers and production

⭐ Tear Film Break-Up Time (TBUT) < 10s is a key indicator of evaporative dry eye disease (EDED).

Etiopathogenesis - Why So Dry?

  • Core Problem: Tear film instability → hyperosmolarity, inflammation, surface damage.
  • Two Main Pathways:
    • Aqueous Deficient (ADDE): ↓ tear production.
      • Sjögren's: Autoimmune; lacrimal/salivary glands.
      • Non-Sjögren's: Lacrimal dysfunction (age, inflammation, drugs e.g., antihistamines, β-blockers).
    • Evaporative (EDE): ↑ tear evaporation.
      • Intrinsic: Meibomian Gland Dysfunction (MGD) - most common DED cause.
      • Extrinsic: Vit A deficiency, preservatives (BAK), contact lenses, low blink.
  • The Vicious Cycle of DED:
![Dry eye disease vicious cycle](https://ylbwdadhbcjolwylidja.supabase.co/storage/v1/object/public/notes/L1/Ophthalmology_Diseases_of_the_Cornea_Dry_Eye_Disease/bc9bc5ef-bebc-4a0b-bcbd-21220a5af3c3.jpg)

⭐ Inflammation (cytokines like IL-1, MMP-9) is a key driver in DED's vicious cycle, common to both ADDE & EDE.

Classification & Clinical Features - Dryness Decoded

  • Two Main Categories (DEWS II):
    • Aqueous Deficient (ADDE):
      • Sjögren Syndrome (SSDE): Autoimmune.
      • Non-Sjögren (NSSDE): Lacrimal damage, ↓reflex secretion.
    • Evaporative (EDE):
      • Intrinsic: Meibomian Gland Dysfunction (MGD), poor lid apposition.
      • Extrinsic: Vitamin A deficiency, preservatives, contact lens.
  • Symptoms: Dryness, grittiness, burning, photophobia, fluctuating vision.
  • Signs:
    • ↓ Tear Break-Up Time (TBUT) < 10s.
    • Corneal/conjunctival staining (fluorescein, lissamine green).
    • ↓ Schirmer test (e.g., < 5mm/5min in SSDE).
    • Lid margin changes (MGD signs). Lissamine green staining showing conjunctival damage in DED

⭐ Meibomian Gland Dysfunction (MGD) is the leading cause of Evaporative Dry Eye (EDE) worldwide.

Diagnostic Workup - Tear Test Time

  • Schirmer's Test: Assesses tear production.
    • Schirmer I (no anesthesia): Basal + Reflex. Normal: >15 mm/5min. DED: <10 mm (mild), <5 mm (severe).
    • Schirmer II (anesthesia): Basal secretion.
  • Tear Film Break-Up Time (TBUT): Evaluates tear film stability.
    • Fluorescein instilled. Normal: >10 sec. DED: <10 sec.

    ⭐ TBUT <5 sec strongly indicates severe DED & tear instability.

  • Ocular Surface Staining:
    • Fluorescein: Detects corneal epithelial defects.
    • Lissamine Green / Rose Bengal: Stains devitalized cells.
  • Advanced: Tear osmolarity (>308 mOsm/L), MMP-9 levels.

Management Strategies - Moisture Mission

  • Goal: Restore homeostasis, improve tear stability, reduce symptoms.
  • Stepwise Approach:
    • Level 1:
      • Education, environmental mods.
      • Artificial tears (ATs): Preservative-free (PF) if >4 uses/day. Lipid-based for MGD.
      • Lid hygiene (MGD).
    • Level 2 (if inadequate):
      • Punctal occlusion.
      • Topical anti-inflammatories:
        • Corticosteroids (Loteprednol): short-term. ⚠️ IOP.
        • Cyclosporine A (0.05%), Lifitegrast: long-term. 📌 (CALI: Cyclo & Lifi)
    • Level 3 (severe DED):
      • Autologous Serum Eye Drops (ASEDs).
      • Oral secretagogues (Pilocarpine).
      • Therapeutic contact lenses.

⭐ Cyclosporine A (0.05%) increases tear production by inhibiting T-cell activation; may take 3-6 months for full effect.

High‑Yield Points - ⚡ Biggest Takeaways

  • Dry Eye Disease (DED): Multifactorial ocular surface disease from tear film instability.
  • Types: Aqueous Deficient (e.g., Sjögren's) & Evaporative (most common, e.g., MGD).
  • Symptoms: Burning, grittiness, foreign body sensation, fluctuating vision.
  • Key tests: TBUT < 10s, Schirmer's < 10mm/5min, corneal staining.
  • Meibomian Gland Dysfunction (MGD) is the most common cause of DED.
  • Management: Artificial tears, cyclosporine A, lifitegrast, punctal plugs, lid hygiene.
  • Sjögren's syndrome: Severe DED; associated with anti-Ro/SSA & anti-La/SSB antibodies.

Practice Questions: Dry Eye Disease

Test your understanding with these related questions

A 67-year-old man with Parkinson disease has experienced an increasingly dry mouth for the past 3 months, and this interferes with eating and swallowing. He has noted dry eyes as well. On physical examination, he has minimal tremor at rest; there are no other abnormal findings. Laboratory studies show no detectable autoantibodies. Which of the following is the most likely cause for his findings?

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Flashcards: Dry Eye Disease

1/10

The corneal layer involved in Gelatinous drop-like dystrophy is _____

TAP TO REVEAL ANSWER

The corneal layer involved in Gelatinous drop-like dystrophy is _____

epithelium

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