Embryology of the Eye

Introduction

• Focus on the development of the eye.
• Involves two germinal layers: ectoderm and mesoderm.
• Endoderm does not participate.

Ectoderm Participation

• Three Parts: Surface ectoderm, neuroectoderm, and neural crest cells.
• Neural Crest Cells: Surround neuroectoderm, forming mesenchyme with mesoderm.

Stages of Eye Development

Optic Groove Formation

• Located in the forebrain.
• Forms optic vesicle by the third week of gestation.
• Optic Stalk: Becomes the future optic nerve.

Lens Formation

• Surface Ectoderm: Thickens to form lens placode.
• Invaginates to form lens pit and eventually lens vesicle.
• Lens Vesicle: Future crystalline lens.

Optic Cup Formation

• Optic vesicle forms optic cup.
• Optic Cup Layers:
  • Outer Layer: Retinal pigment epithelium.
  • Inner Layer: Neurosensory retina.

Role of Neural Crest Cells and Mesenchyme

• Form ocular structures: sclera, Descemet's membrane, endothelium, and orbital bones.
• Nourishment: Lens vesicle initially nourished by hyaloid artery/vein, later by aqueous humor.

Surface Ectoderm Contributions

• Forms eyelid epithelium, corneal epithelium, and eyelid skin.
• Responsible for glands of Krause and Wolfring.

Neuroectoderm Contributions

• Forms ciliary body, iris, and optic nerve.

Additional Contributions:

• Neuroectoderm:
  • Ciliary body epithelium and iris epithelium.
  • Optic nerve formation.
• Neural Crest Cells:
  • Corneal stroma and endothelium.
  • Trabecular meshwork, ciliary body, and ganglion.
• Mesoderm:
  • Development of extraocular muscles, sclera, and various eye muscles.
  • Blood vessel endothelium.

Conclusion

• Presentation aimed to provide a brief overview of eye embryology.
• Understanding the process aids in syllabus comprehension.