Ocular Anatomy: Anterior vs Posterior Segment, RetinaChoroidOptic nerveRetinaChoroidOptic nerve

👁 Ocular Anatomy: Anterior vs Posterior Segment

The human eye is structurally divided into two major parts:
Anterior Segment and Posterior Segment,
separated by the posterior lens capsule / anterior vitreous face.

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🔹 Anterior Segment

• Structures:
  • Cornea
  • Iris
  • Ciliary body
  • Lens
• Chambers:
  • In front of the iris: Anterior chamber
  • Behind the iris: Posterior chamber
• Fluid:
  • Aqueous humor
  • Flow: Produced by ciliary body → fills posterior chamber → flows through pupil → fills anterior chamber → drains via trabecular meshwork
  • This flow regulates intraocular pressure (IOP) (normal: 10–21 mmHg)

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🔸 Posterior Segment

• Structures:
  • Retina
  • Choroid
  • Optic nerve
• Cavity:
  • Vitreous cavity, filled with vitreous humor
• Vitreous Composition:
  • Collagen fibers + Hyaluronic acid
  • Young eyes: gel state → maintains clarity
  • With aging: vitreous liquefaction → collagen clumps → floaters

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✅ Summary Table

SegmentKey StructuresFluidMain Role

Anterior	Cornea, Iris, Ciliary Body, Lens	Aqueous humor	IOP regulation, nourishment
Posterior	Retina, Choroid, Optic Nerve	Vitreous humor	Light transmission, support