Lecture Notes: Histology of the Cornea

Introduction

• The cornea is composed of five distinct layers.
• It is a unique, transparent structure that replaces the sclera in the anterior 1/6 of the eyeball.
• Notable characteristics include being colorless, avascular, and having a rich nerve supply.

Layers of the Cornea

1. Corneal Epithelium

• The outermost layer.
• Made of non-keratinized stratified squamous epithelium.

2. Bowman's Membrane (Anterior Limiting Lamina)

• Composed of fine collagen fibrils embedded in a matrix.
• Provides stability and strength to the cornea.

3. Corneal Stroma (Substantia Propria)

• The thickest layer of the cornea.
• Made up of type I collagen fibers embedded in ground substance.
• Contains fibroblasts, also known as "keratocytes" or "corneal corpuscles," which appear flattened and star-shaped.

4. Descemet's Membrane (Posterior Limiting Lamina)

• A true basement membrane located deep to the substantia propria.

5. Corneal Endothelium (Posterior Cuboidal Epithelium)

• Comprises a single layer of flattened cells lining the posterior surface of the cornea.
• In contact with the aqueous humor of the anterior chamber.
• Functions:
  • Transfers ions.
  • Pumps out excess fluid, maintaining corneal transparency.
  • Contains numerous mitochondria and is united by desmosomes.

Summary

• The corneal structure is vital for eye function, with each layer having specific roles in maintaining transparency and structural integrity.

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