Human Eye Structure

Front View of Human Eye

Internal Structure of Eye

Structures of the Eyes

Sclera, Cornea, Choroid, Ciliary Body, Suspensory Ligaments, Iris, Retina, Yellow Spot, Blind Spot, Lens, Aqueous Humour, Vitreous Humour

Sclera

-Tough, white inelastic layer that covers and protects the inner structures of the eye

-Maintains shape of eye

Cornea

-Transparent continuation of sclera which is convex

-Allows light to pass through

-Causes refraction, creating image on retina

Choroid

-Dark coloured layer containing blood vessels & pigments

-Pigments absorb light and prevent reflection of light

-Blood vessels supply oxygen & nutrients

Ciliary Body

-Thickened part at anterior of choroid

-Contains ciliary muscles

-Ciliary muscles alter tension on the suspensory ligaments

Suspensory Ligaments

-Ligaments attached to the ciliary body

-Holds lens in position during accommodation

-Tension changes alters shape of lens

Iris

-Coloured portion of eye, with opening at the centre

-Controls amount of light entering the eye through pupillary mechanism

Retina

-Inner layer of eye containing the rods and cones

-Rods respond to low intensity light, provides night and peripheral vision

-Cones respond to bright light, provides clear and sharp colour vision

-Neurons carry impulses from rod & cones through optic nerve to cerebrum

Yellow Spot

-Small indentation at back of eyeball containing most of the cones

-Area of clearest vision

Blind Spot

-Small area on retina, below yellow spot, contains no rods, cones, therefore no vision

-Area where blood vessels enter eye

-Area where optic nerve leaves eye

Lens

-Transparent, Elastic & Biconvex structure behind pupil

-Held in place by suspensory ligaments

-Allows light to pass through

-Changes shape to allow eye to focus on near and distant objects

Aqueous Humour

-Watery fluid in space between cornea and lens

-Maintains shape of cornea

-plays a small role in the refraction of the incoming light

Vitreous Humour

-Jelly-like substance found behind lens

-Maintains shape of eyeball

-plays a small role in the refraction of the incoming light