THE EYE
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Transcript of THE EYE
THE EYETHE EYECHAPTER 10
QOD #1: Pre-TestQOD #1: Pre-Test1.) What are the 5 senses?2.) T/F Of all the sensory receptors in the
body, 70% are in the eyes.3.) T/F Your eyebrows have no function.4.) T/F If you are colorblind, you do not
see any color.5.) T/F If you are farsighted, you cannot
see objects that are in close proximity.6.) _________ is caused by an increase in
pressure in the eye.
The eyeThe eye70% of sensory receptors in the body are found
here.Housed in the orbit of skull and surrounded by
fat, blood vessels, nerves, and connective tissues.2.5cm in diameter3 layers (tunics/coats)
◦ Outer layer (fibrous) Protective, refracts light Includes cornea and sclera
◦ Middle layer (vascular) Contains pigments to keep eye dark inside Includes choroid coat, ciliary body, lens, iris, pupil, aqueous
humor.
◦ Inner layer (nervous/sensory) Visual receptors Contains retina, fovea, optic disc, vitreous humor
Pathway of LightPathway of Light
CorneaAqueous humorPupilLensVitreous humor Retina
EYE PHYSIOLOGYRefraction: occurs when light
waves are bent◦Normal◦Image is upside down◦Visual cortex of brain interprets it in its
proper position
Physiology cont…Physiology cont…Accomodation:
◦ Occurs when the lens adjusts its shape to focus on objects.
◦ Ciliary muscles and suspensory ligaments aid in doing this When the ligaments pull outward the lens
flattens and focuses on distant objects When ligaments are relaxed the lens is more convex (thickens) focusing on closer objects
VISUAL ACUITYVISUAL ACUITYOphthalmoscope: instrument
that illuminates the interior of eyeball allowing the inside to be seen.
Snellen eye chart: ◦ measure acuity◦ 20/20 normal vision◦Higher the number the poorer the vision
Eye problemsEye problemsMyopia: near sightedHyperopia: far sightedEmmetropia: normal visionAstigmatism: cornea/lens developed
an irregular shapeStrabismus: cross-eyedDiplopia: double vision (can be caused
by one eye deviating from line of vision).Blindness: most common cause is loss
of transparency of the cornea◦ Cornea transplant (high success rate b/c no
blood vessels)
Eye problems cont..Eye problems cont..Cataract: lens becomes cloudy (laser
surgery to fix)
Glaucoma: increase in intraocular pressure, caused by an increase in aqueous humorTonometer: instrument measuring pressure
Night blindness: poor vision in dim light resulting from a vitamin A deficiency.
Normal Vision
Color Blind
Color Blindness: Genetic disorder carried on the X chromosome. Most common is red/green color blindness.
Normal Vision
Color Blind