QS Study

Layers of Eyeball

The eye is the organ of sight. An eyeball is a bilateral and spherical organ, which houses the structures responsible for vision. It is a spherical structure measuring about 2.5 cm in diameter.

An eyeball is made up of three concentric coats, these are –

Outer or fibrous coat: The fibrous layer of the eye is the outermost layer. It consists of the sclera and the cornea. Their main functions are to provide shape to the eye and support the deeper structures.

  • The sclera provides attachment to the extraocular muscles; these muscles are responsible for the movement of the eye. It is visible as the white part of the eye.
  • The cornea is transparent and positioned centrally at the front of the eye.

Layers of Eyeball 1

Fig: Layers of Eyeball

The middle or vascular coat (uveal tract): The vascular layer of the eye lies underneath the fibrous layer. It consists of the choroid, the ciliary body, and the iris.

  • Choroid – a layer of connective tissue and blood vessels.
  • Ciliary body – these are attached to the lens of the eye by the ciliary processes
  • Iris – circular structure, with an aperture in the center (the pupil).

The inner or nervous coat is the retina: Light entering the eyeball passes through several refracting media, from before backward these are the cornea, the aqueous humor, the lens, and the vitreous body.

  • Neural layer – the innermost layer of the retina. It is located posteriorly and laterally in the eye.
  • Pigmented layer – the outer layer of the retina. It continues around the whole inner surface of the eye.
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