eye.pptx

MEDICAL

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 (2 nd 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

4. 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.

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

6. 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

7. 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

8. 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

9. 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.

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

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