Pupil Opening in iris Color determined by: Number of melanocytes No melanocytes = blue eyes Increasing number of melanocytes = green, brown and black eyes Albinos = Pale gray or gray blue eyes
Susensory Ligaments Hold lens in place
AKA: Retina Innermost layer Photoreceptors—cells that detect light Rods—light sensitive “low light vision” Cones—color Sharper images Requires light
Macula lutea Where most cones are In center—fovea centralis
Optic Disc Origin of optic nerve Contains blood vessels No photoreceptors “Blind spot” Brain fills in missing information
Anterior chamber—cornea to iris Posterior chamber—iris to lens Aqueous humor—fills both chambers Maintains shape of eye Transports wastes and nutrients Vitreous body—in posterior chamber Maintains shape of eye
Interference with circulation Increase in pressure Leads to blindness if untreated
Focus image on photoreceptors Transparent Contract and changes shape
Lens loses transparency Due to drugs, injury or radiation Most common: senile cataracts Becomes cloudy with age Visual clarity fades Need bright lights to see Treatment: Remove old lens Replace with artificial lens Fine tune with glasses or contacts No treatment = blindness