Eye
Cornea
Anatomy and histology

Author: Nat Pernick, M.D. (see Authors page)

Revised: 1 May 2018, last major update October 2013

Copyright: (c) 2004-2018, PathologyOutlines.com, Inc.

PubMed Search: Cornea [title] anatomy [title] and histology

Cite this page: Pernick, N. Cornea: anatomy and histology. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/eyecorneaanatomy.html. Accessed July 21st, 2018.
Definition / general
  • Wider than tall (11.7 mm horizontally vs. 10.6 mm vertically)
  • Thickness varies from 0.5 mm (central) to 0.67 mm (peripheral)
  • Cornea and overlying tear film are major refractive surface of eye, not the lens
  • 6 distinct layers (outside to inside):
      1. Outer epithelium: stratified squamous, nonkeratinized, 5 layers thick centrally, thicker peripherally, polygonal at basal layer but flatten as they approach surface; basal cells may have mitotic figures; Langerhans cells are CD1a+; note: layers often “rubbed off” while grossing specimen
      2. Epithelial basal lamina (basement membrane): highlighted with PAS stain
      3. Bowman layer: most anterior stroma, acellular, 8 - 14 microns thick, not a true basement membrane, composed of randomly oriented delicate collagen fibers, does not regenerate
      4. Stroma: also called substantia propria, no blood vessels or lymphatics, 90% of cornea's thickness, contains regularly spaced collagen fibrils; normally separated by glycoprotein and mucoprotein which makes cornea transparent; normally see stromal lamellae separated by clefts, a processing artifact, absence of clefts is caused by stroma edema (causes corneal "clouding"), due to damage of "endothelium"
      5. Descemet [pronounced DEZMET] membrane: a true basal lamina produced by underlying corneal endothelial cells; 3 - 4 microns at birth, 10 - 12 microns in adults; does not regenerate; site of copper deposition in Kayser-Fleisher ring of Wilson disease
      6. "Endothelium": single layer of very flat cells, does not regenerate, functions as pump to keeps cornea dehydrated and transparent
        • Neural crest origin (S100+); does NOT line blood vessels or lymphatic spaces; directly contacts aqueous humor of anterior chamber, often “rubbed off” while grossing specimen
Vasculature
  • No blood vessels or lymphatics within cornea
  • Arterial plexus is present at junction of cornea and sclera
  • Is also nourished by aqueous humor of anterior chamber
Hasall-Henle bodies (warts)
  • Focal excrescences that form on peripheral Descemet membrane with normal aging
  • Not seen in surgically excised corneal buttons because are too peripheral in location
Myopia
  • Eye too long for its refractive power
Hyperopia
  • Eye too short for its refractive power
Laser assisted in situ keratomileusis (LASIK)
  • Sculpt cornea and change its refractive properties to eliminate need for glasses
Microscopic (histologic) images

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Full thickness

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Epithelium and Bowman layer

Drawings

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Cornea

Positive stains
Negative stains
Additional references