The eye has three layers - an outer fibrous layer, middle vascular layer, and inner nervous tissue layer. The outer layer includes the sclera and transparent cornea. The middle layer is made up of the choroid, ciliary body, and iris. The inner layer is the retina. The ciliary body secretes aqueous fluid and controls the lens thickness through contraction of the ciliary muscles. The iris lies in front of the lens and controls the size of the pupil through sympathetic and parasympathetic nerves. The retina contains light-sensitive rods and cones that convert light into nerve impulses.

1. STRUCTURE OF EYE

2. INTRODUCTION:-
• Eye is the organ of the sense of sight
• Situated in the orbital cavity
• Supplied by the optic nerve (2nd cranial nerve)
• Spherical in shape

3. Layers of the eye:-
• Outer fibrous layer- sclera and cornea
• Middle vascular layer- choroid, ciliary body,
iris.
• Inner nervous tissue layer-retina

5. SCLERA AND CORNEA
• Sclera forms the outermost layer in the
posterior and lateral aspects of the eye ball.
• Sclera is continuous anteriorly with the
transparent cornea.

7. CHOROID
• It lines the posterior five sixths of the inner
surface of the sclera.
• Deep chocolate brown in colour
• Rich in blood vessels

8. CILIARY BODY
• Anterior continuation of the choroid
• Consists ciliary muscles
• Contraction and relaxation of the ciliary
muscle changes the thickness of the lens
• Ciliary body secretes aqueous fluid

9. IRIS
• It is the visible coloured part of the eye.
• Lies behind the cornea infront of the lens.
• Iris is supplied by parasympathetic and
sympathetic nerves
• Parasympathetic stimulation constricts the
pupil and sympathetic stimulation dilates it
• Colour of the iris is genetically determined and
depends on number of pigment cells present

10. LENS
• Lens is a highly elastic , circular biconvex body,
lying immediately behind the pupil.
• It is suspended from the ciliary body by the
suspensory ligament

11. RETINA
• It is the innermost layer of the wall of the eye.
• It is an extremely delicate structure
• Has a layer of sensory receptor cells: rods and
cones
• Rods and cones contain photosensitive
pigments that convert light rays into nerve
impulses.
• Rods are sensitive to dim light & cones are
sensitive to bright light.

12. Blood supply to the
eye
• Arterial supply:- Ciliary arteries and central
retinal artery
• Venous drainage:- central retinal vein.

13. ACCESSORY ORGANS OF THE EYE:-
• Eyebrows
• Eyelids & eyelashes
• Lacrimal apparatus