Eye - Structure: 3 Tunics (=Layers)
Iris
Anterior "Colored donut of muscle" (Intrinsic muscle) opening = pupil Sphincter pupillae Dilator pupillae Refulates amount of light intering the eye
Cornea
Anterior 1/6 of eye Transparent
Lens
Biconvex Transparent Flexible Changes shape to allow for the focusing of light on the retina
Rods
Black and white vision, respond to low intensity light (night)
Cones
Color vision Respond to high intensity light (daylight)
Internal (Sensory) Tunic
Composed of the retina Pigmented layer Neural layer
Ciliary Processes
Contain capillaries that secrete aqueous humor Part of ciliary body
Neural Layer
Inner layer Composed of photoreceptors Rods Cones
Macula Lutea
Lateral to blind spot Oval region Contain Fovea centralis
Fovea Centralis
Minute pit in center of macula lutea Contains only cones Where critical "detailed" viewing takes place
Pigmented Layer
Outer layers of internal tunic No photoreceptors Stores vitamin A
Fibrous Tunic
Outermost, avascular Sclera Cornea
Ciliary Body
Part of vascular tunic Ciliary (an intrinsic muscle) which is attached to the lens by Suspensory ligaments. Muscles changes shape of lens (=focus)
Choroid
Posterior 2/3 of eye Vascular and pigmented Nourishes retina and sclera by diffusion
Sclera
Posterior 5/6 of eye Nontransparent The "white" of the eye
Sphincter Pupillae
Pupillary constrictor Contricts pupil
Dilator Pupillae
Pupillary dilator Dilates pupil
Vascular Tunic
Uvea Middle Layer Choroid Ciliary Body Iris
Blind Spot
Where the optic nerve exits the eye Optic Disk No rods of cones