Corneal Degenerations

Corneal Degenerations - Age & Wear Unveiled

Corneal degenerations are acquired, progressive, non-familial corneal changes, often age-related or secondary to local/systemic factors.

• Key Differences: Degenerations vs. Dystrophies

  Feature	Corneal Degenerations	Corneal Dystrophies
  Onset	Later life (Age-related)	Early life
  Laterality	Often Unilateral/Asymmetric	Usually Bilateral, Symmetric
  Inheritance	Sporadic (Non-familial)	Often Hereditary
  Inflammation	May be present	Usually Absent
  Vascularization	Often Present	Usually Absent
  Progression	Variable	Slow, Relentless

• Common Etiological Factors:

  • Age (Senile changes)
  • Chronic inflammation (e.g., keratitis, uveitis)
  • Trauma (mechanical, chemical)
  • Systemic diseases (e.g., gout, hypercalcemia)
  • UV exposure

⭐ Corneal degenerations are typically acquired, often unilateral or asymmetric, and may be associated with vascularization, unlike most dystrophies.

Peripheral Problems - Thinning & Rings

• Arcus Senilis

  • Description: Common, bilateral, yellowish-white lipid deposition in peripheral corneal stroma, separated from limbus by a clear "lucid interval of Vogt".

  • Etiology: Usually age-related (>50 yrs). If present in individuals <40 yrs (Arcus Juvenilis), indicates likely hyperlipidemia.

  • Clinical Significance: Benign in elderly.

  ⭐ Arcus senilis in individuals <40 years (arcus juvenilis) warrants investigation for hyperlipidemia.

• Terrien Marginal Degeneration (TMD)

  • Description: Rare, idiopathic, painless, slowly progressive, non-inflammatory thinning of peripheral cornea. Typically bilateral, asymmetric, starting superonasally. 📌 Terrien = Thinning, Top (superiorly).
  • Features: Intact epithelium over thinned area, lipid deposition at leading edge of thinning, superficial vascularization, characteristic against-the-rule astigmatism.
  • Complications: Risk of spontaneous or traumatic globe perforation.

Central & Surface Changes - Calcium & Nodules

• Band Keratopathy: 📌 Bad Calcium.

  • Desc: Calcium deposition in Bowman's layer, typically in the interpalpebral fissure. Presents with a 'Swiss cheese' appearance (lucent holes within the band).

  • Etiol:

    • Chronic ocular disease: Uveitis, phthisis bulbi.
    • Systemic: Hypercalcemia, gout, sarcoidosis.
    • Other: Intraocular silicone oil.

  • Sx: ↓ Vision, foreign body sensation (FBS), irritation.

  • Tx: Chelation with Ethylenediaminetetraacetic acid (EDTA).

  ⭐ Band keratopathy typically starts peripherally in the interpalpebral fissure and progresses centrally, with lucent holes within the band.

• Salzmann Nodular Degeneration:

  • Desc: Smooth, opaque, elevated bluish-white nodules, typically in the mid-periphery or periphery.
  • Histo: Hyaline degeneration, disorganized lamellar collagen.
  • Assoc: Chronic keratitis (e.g., phlyctenular, trachoma), trauma, prolonged contact lens wear. Strong female predilection.

• Lipid Keratopathy:

  • Desc: Dense, yellow-white, refractile lipid deposits within the corneal stroma.
  • Types:
    • Primary (idiopathic): Rare; occurs without prior corneal vascularization.
    • Secondary: Common; develops following corneal vascularization from chronic irritation, injury, or herpetic keratitis.

High‑Yield Points - ⚡ Biggest Takeaways

• Arcus senilis: Commonest stromal lipid deposition, clear limbal zone; check lipids if < 40 yrs.
• Band Keratopathy: Interpalpebral calcium in Bowman's; linked to chronic uveitis, hypercalcemia.
• Salzmann's Nodular: Bluish-white hyaline nodules (post-chronic keratitis).
• Terrien's Marginal: Painless peripheral thinning, vascularized; risk of atraumatic perforation.
• Pellucid Marginal: Inferior crescentic thinning, "crab-claw" topo; high ATR astigmatism.
• Spheroidal Degeneration: Amber granules in stroma; linked to UV exposure.