CHOROID -

• Thin, net like made up of connective tissue, rich in blood vessels.
• Pigment present, red in rabbit, brown or black in man. It reduces internal reflection.
• Except cornea this layer is attached to sclerotic.
• In front of cornea this layer froms a thin coloured partition i.e. iris. IRIS -
• It is perforated in the middle by an aperture pupil. Iris is highly muscular
• Circular and radial muscles are present. Circular muscles are sphincter type. Radial muscles are dilator type.
• On contraction of circular muscles diameter of pupil is reduced it is myosis, it takes place in sharp light.
• On contraction of radial muscles diameter of pupil is increased, it is mydriosis, it occurs in dimlight.
• Atropine is used to dialate pupil.

• Basal part of iris is highly muscular having circular, radial and obligue muscles. It is known as cilliary body.
• On its free surface 70 - 80 cilliary processes present secretes aquous humour in aquous chamber.
• Cilliary body also affects convexity of lens.