1. Vision
The eye is the organ of the sense of sight situated in the orbital cavity and it is supplied by the optic
nerve (II cranial nerve).
It is the most spherical in shape and is about 2.5 cm in diameter. The space between the eye and the
orbital cavity is occupied by adipose tissue. The bony walls of the orbit and the fat help to protect the
eye from injury.
Structure of the eye ball:
Eye ball is generally desired as sphere, but it is oval not circular. It is about 1 inch diameter transparent
in front and composed of three layers.
1. The outer fibrous layers – sclera, cornea
2. The middle vascular layer- choroid, ciliary body, iris
3. The inner nervous tissues layer- retina
Structures inside of the eye ball are lens, aqueous fluid, and vitreous body
Lens: is a thick, transparent, highly elastic, circular, biconvex disc lying immediately behind the pupil and
iris, within the cavity of the eyeball. It consists of fibers enclosed in a capsule and held in position by
encircling (suspensory ligaments) zonnular fibers, which attach to the ciliary processes. The thickness of
lens is controlled by the ciliary muscle through the suspensory ligaments. The lens helps focus images on
the retina to facilitate clear vision.
The anterior chamber lies between cornea & iris and the posterior chamber lies between iris and in
front of lens. Both chambers of anterior cavity field with aqueous humor which nourishes lens and
cornea. From the anterior chamber aqueous humor drain into scleral venous sinus and then in to blood.
