cataract

• Anatomy of the cornea:

  • The cornea is the clear transparent anterior 1/6 of the fibrous tunic of the eyeball
  • Features of the cornea:
  • Smooth surface
  • Avascular
  • Richly supplied with nerve fibers
  • Most powerful refractive media of the eye (42 D)
  • Horizontal diameter is 11.6 mm and vertical is 10.6 mm
  • Composed of 5 layers:

  1. Epithelium

  2. Bowman’s membrane

  3. Substantia propria (stroma)

  4. Descemet’s membrane

  5. Endothelium
• Inflammation of the cornea:

  • Divided into 2 types:

  1. Ulcerative keratitis: destruction of epithelium and underlying stroma

  2. Non-ulcerative keratitis: only affects the stroma

  • Classification of ulcerative keratitis:
  • Primary corneal ulcer: bacterial, viral, and mycotic
  • Secondary corneal ulcer: occurs as a complication of chronic conjunctivitis
  • Bacterial ulcerative keratitis (hypopion ulcer):
  • Symptoms: pain, photophobia, lacrimation, blepharospasm, defective vision
• • Signs: circumcorneal vascular injection, haziness of corneal surface, central disc-shaped ulcer, hypopion present
  • Complications: anterior uveitis, secondary glaucoma, corneal opacity, keratectasia
  • Treatment: local antibiotic, atropine, promotion of re-epithelialization
• Viral ulcerative keratitis (herpes simplex keratitis):

  • Symptoms: photophobia, lacrimation, pain, foreign body sensation
  • Signs: dendritic epithelial ulcer, ciliary injection
  • Treatment: anti-viral eye ointment (acyclovir), Vitamin C
• Keratoconus:

  • Non-inflammatory conical protrusion of the center of the cornea
  • Results in a high degree of irregular myopia
  • Symptoms: defective vision
  • Signs: cone-shaped cornea, Manson’s sign positive
  • Treatment: optical treatment (glasses or hard contact lens), keratoplasty (corneal grafting)
• Corneal opacity:

  • Definition: disorder of the cornea causing serious vision problems
  • Causes: infection, injury, or inflammation of the eye
  • Risk factors: Vitamin A deficiency, measles, foreign bodies, eye injury, herpes simplex virus, other infections, prolonged contact lens wear
  • Symptoms and signs: vision decrease or loss, pain or foreign body sensation, eye redness or light sensitivity, cloudy or milky appearance on the eye
  • Treatment: local steroids, glasses, contact lenses, keratoplasty
• Prevention of corneal opacity:

  • Steps to reduce chance of developing corneal opacity:
  • Avoid injuring the eye and wear eye protection
  • Proper care of contact lenses
  • Seek immediate medical attention for eye infections, injuries, or changes in vision