Eyes

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Eyes Ears

• BS
• Chapter 11

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The Senses

• The sensory system serves to protect an
  individual by detecting changes in the
  environment
• An external environmental stimuli travels through
  the CNS into a sensory (afferent) nerve and
  leaves through an motor (efferent) nerve to the
  effector (muscle or gland or organ)

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Stimulus

• The initiation of an impulse in a nerve
• An excitant or irritant

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Receptor

• The part of the nervous system that detects a
  stimulus is called a receptor

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Ophthalmology

• The health and science dealing with the eye and
  its diseases

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Ophthalmologist

• A Physician who specializes in the treatment of
  disorders of the eye

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The Eye Vision

• In the embryo, the eye is formed as an out -
  pocketing of
• the brain
• The eye is very delicate and is
• greatly protected

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Protection of the eye

• The skull bones help form the walls of the eyes
  orbit or cavity
• The skull protects more than ½ of the dorsal part
  of the eye
• The eyelid protects the front of the eye. The
  eyelid can be closed and keeps the particles out
  of the eye. Blinking helps to keep the eye
  lubricated

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• We have a muscle that when it contracts, keeps
  the eye open. In old age, this muscle weakens
  and the eye doesnt stay open, this is called
  Ptosis
• Eyelashes and eyebrows keep foreign matter out of
  the eye

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Conjunctiva

• A thin membrane that lines the eyelid and covers
  the anterior portion of the eyeball
• You can see the conjunctiva if you pull the lower
  eyelid down, its the pink part
• Cells within the conjunctiva produce mucus that
  aids in lubricating the eye
• As the conjunctiva extends from the eyelid to the
  front of the eye, a sac is formed where eye drops
  can be placed

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Conjunctivitis - Pinkeye

• The membrane that lines the eyelid becomes
  irritated or a pathogen enters
• The treatment is usually a general eye drop such
  as gentamycin opthalmic drops. Cortisone can be
  added to the drops if there is a great deal of
  itching and burning.
• Conjunctivitis can be contagious, good
  handwashing and non-sharing of pillow,
  washclothes is encouraged. Enc. Pt NOT to rub
  eyes, infection may spread

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Conjunctivitis
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Pt looking up conjunctiva is seen

• 1) The Limbus is the junction of the
  conjunctiva and cornea.
• 2) The conjunctiva
• 3) The tarsal conjunctiva
• 4) The tarsus (more
• conjunctiva)
• 5) Punctum
• 6) The marginal conjunctiva is at the eyelid
  margin where the epithelium will begin to be
  keratinized.

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Lacrimal Duct or gland

• Tears are produced by the lacrimal gland
• Tears are formed to lubricate the cornea
• and conjunctiva
• The actual lacrimal
• gland is near the outer eyebrow

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Tears

• Fluid produced by the lacrimal gland to moisten
  the cornea and conjunctiva contain the enzyme
  lysozyme.
• This enzyme lysozyme, protects against bacterial
  invasion
• Tears drain into the inner canthus and drain into
  the punctum which is a hole in the inner eye,
  this drains into the nasolacrimal duct

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Where do tears go

• If tears arent streaming down ones cheeks, they
  are carried into ducts near the nasal corner of
  the eye where they drain into the nose by way of
  the nasolacrimal ducts
• Once the tears run through these ducts, they
  cause a runny nose. These ducts can be clogged
  at times

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Coats of the eyeball

• The eyeball has 3 coats or tunics
• 1. Sclera
• 2. Choroid
• 3. Retina

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Sclera

• This is the white of the eye
• The sclera is made of tough connective tissue
• The sclera circles all the way around the back of
  the eyeball and when it reaches the front of the
  eyeball, it becomes the cornea

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Choroid

• This is the delicate network of connective middle
  layer
• This choroid layer is laced with blood vessels
  and brown pigment and prevents incoming light
  rays from scattering and reflecting off the inner
  surface of the eye

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CHOROID
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Back of the eye

• The blood vessels in the back of the eye can
  reveal signs of disease (see picture on pg 185)
• One can see these vessels by using an
  opthalmascope

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Retina

• This complex structure has multiple layers and
  the retina is the actual receptor layer of the
  eye
• The multiple layers contains 10 layers of rods
  and cones which generate the nerve impulses
  associated with vision
• The rods and cones in the retina requires vitamin
  A. If Vit A is lacking, a person may have
  difficulty seeing in dim light to activate the
  rods. A deficiency in vit. A night blindness

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Rods Cones the receptor cells of the eyes

• RODS sensitive to light, rods function in dim
  light, images are not sharp, you see in gray.
  There are about 120 million rods in each retina.
  Rods are distributed more towards the front of
  the retina
• CONES function in bright light, sensitive to
  color such as red, green, blue and give sharp
  images. There are about 6 million cones in each
  retina. Cones are located near the center of the
  retina in a pitted area known as the fovea
  centralis

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Rods Cones in the Eye
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Entering a dark room

• When you enter a dark movie theatre, you cannot
  see for a moment. Your pupils enlarge so you can
  try and see more clearly.
• At this time, the rods are beginning to work,
  when you can see again, the images are blurred
  and you can only see objects in gray because the
  rods are not able to differentiate color

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Nerve impulses from rods and cones

• Nerve impulses from rods and cones flow into
  sensory neurons that eventually form the optic
  nerve
• The optic nerve, which is the 2nd cranial nerve,
  connects to the retina at the back of the eye and
  is then connected to the occiptial lobe of the
  brain
• The impulses travel through the optic nerve to
  the visual center of the brain which is the
  occipital lobe

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Lights path through the eye (how does light
travel)

• As light rays pass through the eye towards the
  retina, the rays travel through a series of
  transparent, colorless parts
• On the way, the light rays become bent
  (refracted). This refraction of the rays make it
  possible for light from a very large area, to be
  focused on a very small surface to the retina
  where the receptors are located. At this point,
  the rays also become overrefracted (turned
  upside down and backwards), The visual centers of
  the brain must reverse the images

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Light must pass through these parts in order to
see

• This is from the outside where we see the light
  on into the eye eventually to the retina
• Cornea
• Aqueous humor
• Lens
• Vitreous body

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Cornea

• Is a forward continuation of the sclera (see
  picture on pg 185)
• This part is transparent and colorless whereas
  the sclera we can see is white and opaque
• The cornea has no blood vessels and is well
  nourished by the fluids that constantly wash over
  it
• The cornea can become scarred d/t injury
  decreased vision. The cornea can be transplanted

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Cornea
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Aqueous Humor

• A watery fluid that fills much of the eyeball in
  front of the lens
• The aqueous humor helps maintain the slight
  forward curve of the cornea
• In the area where aqueous humor is found is where
  glaucoma is found

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Aqueous Humor
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Lens

• A clear, circular structure made of firm, elastic
  material. The lens has 2 bulging surfaces and is
  described as bi-convex
• The lens is important in light refraction because
  of the elasticity, the shape of the eye can
  change and its thickness can be adjusted to
  focus light for near or distant vision

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Lens
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Vitreous Body

• Soft jelly-like substance that fills the entire
  space behind the lens. This jelly IS NOT
  replaceable
• The vitreous body helps maintain the shape of the
  eyeball as well in aiding in refraction of light

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Eye Anatomy
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Eye Anatomy

• 1. Cornea in front, in back of eye is sclera
• 2. Aqueous humor
• 3. Lens
• 4. Retina
• 5. Vitreous body

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Anterior Parts of the Eye

• 1. Conjunctiva
• 2. Cornea
• 3. Cilliary body
• 4. Lens

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Muscles of the eye

• Intrinsic Muscles
• Extrinsic Muscles

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Intrinsic Muscles

• In general, these are the circular involuntary
  muscles of the eye.
• These include the muscles around the iris and the
  pupil and this includes the cilliary muscle.

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The ciliary body is a ring of tissue that
encircles the lens. The ciliary body contains
smooth muscle fibers called ciliary muscles that
help to control the shape of the lens. Towards
the posterior surface of the lens there are
ciliary processes which contain capillaries. The
capillaries secrete the fluid (aqueous humor)
into the anterior segment of the eyeball
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Iris

• This is the colored part of the eye. Some colors
  include shades of blue, brown, green, hazel. In
  the center of the iris is the pupil.
• The purpose of the iris is to regulate the amount
  of light entering the eye. In the presence of
  bright light, the cilliary muscles of the iris
  contract, reducing the size of the pupil
  constriction

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Cilliary Muscle stretch the lens

• Is shaped like a flattened ring with a hole the
  size of the outer edge of the iris.
• The cilliary muscle alters the shape of the lens
  during the process of accommodation adjustment
  or adaption of the eye while its trying to focus
  on something, usually far away

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Draw a circle.

• Radial muscles are located around where the iris
  is (think of a radial tire and the treads or like
  the spokes of a bike)
• Circular muscles are around the pupil
• When circular contract, radial relax

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Accommodation

• Adjustment or adaption.
• The adjustment of the eye for various distances
  where it is able to focus the image of an object
  on the retina by changing the curvature of the
  lens
• For near vision, the ciliary muscle contracts
  causing increased rounding of the lens and the
  pupils contract
• The ability to accommodate, decreases with age.

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Pupil

• The contractile opening at the center of the iris
  of the eye
• The pupil contracts when exposed to light and
  when the focus is on a near object
• The pupil dilates when in the dark and when focus
  is on a distant object

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Adjustment of the lens

• Ciliary muscles help the lens get fatter to see
  things up close
• Or
• Thin like a pancake in order to see things far
  away

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Extrinsic Muscles

• These are the 6 ribbon-like voluntary muscles
  attached to the outer surface of the eyeball.
  These muscles coordinate eye movement and the
  opening of the eyelid
• These muscles pull on the eyeball in a
  coordinated fashion so that both eyes center on
  one visual field at the same time (convergence).
  Convergence is necessary to the formation of a
  clear image on the retina

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Extrinsic Muscles of the Eye
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Nerve supply to the eye

• 2 nerves supply the eye
• We will discuss the optic nerve for this ch.

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Optic Nerve

• Carries visual impulses from the rods and cones
  to the brain
• Optic nerve starts from the retina toward the
  medial or nasal side of the eye
• There are no rods or cones in the area of the
  optic nerve but the optic nerve carries impulses
  only from the rods and cones to the brain

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Optic Disc

• Because there are no cones or rods near or around
  the optic nerve, no images can form on the
  retina around the optic nerve, at this point,
  this is known as the blind spot or optic disc

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Close to the optic disc

• There is a tiny depressed or pitted area in the
  retina known as the fovea centralis

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Fovea Centralis

• The fovea is contained within a yellow spot
  called the macula, with age, this macula
  degenerates
• This yellowish fovea, contains the highest
  concentration of cones
• This portion of the area near the optic disc in
  the fovea centralis, is the point of sharpest
  vision

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Vision Problems

• Ptosis drooping of the eyelid related to
  paralysis, can occur after a stroke

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• Amblyopia otherwise known as lazy eye. Can
  be treated with eyeglasses.
• The brain and eyes do not work together properly,
  the brain favors one eye.
• The brain may suppress the visual image from the
  deviating eye to prevent double vision.
• This accounts for 50 of childhood amblyopia

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Amblyopia
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Strabismus

• A deviation of the eye that results from lack of
  coordination of the eyeball muscles. The 2 eyes
  do not work together.
• In children, when the eyes fail to focus on the
  same image, the brain may learn to ignore the
  input from one eye.
• This loss of vision is called amblyopia, and it
  is frequently associated with strabismus
• Convergent strabismus is when the eye deviates
  toward the nasal side and gives the appearance of
  being cross-eyed

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Google says

• Strabismus, more commonly known as cross-eyed or
  wall-eyed, is a vision condition in which a
  person can not align both eyes simultaneously
  under normal conditions. One or both of the eyes
  may turn in, out, up or down. An eye turn may be
  constant (when the eye turns all of the time) or
  intermittent (turning only some of the time, such
  as, under stressful conditions or when ill).
  Whether constant or intermittent, strabismus
  always requires appropriate evaluation and
  treatment. Children do not outgrow strabismus!

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Treatment

• If these disorders are not corrected early, the
  transmission and interpretation of visual
  impulses to the brain is decreased. Muscles
  become weakened in the eye and muscle restoration
  must be rebalanced, glasses, eye patch or surgery
  may be needed

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Normal Vision
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Hyperopia

• Farsightedness caused by a short eyeball, the
  light seen hits the back of the eye (can only see
  far away)
• The focal point is behind the retina because
  light rays cannot bend sharply enough to focus on
  the retina. Objects must be moved far from the
  eye to be seen clearly
• Farsightedness is common in infants but it
  corrects itself when the child uses the eyes more
  for near vision
• Treatment glasses with convex lenses to increase
  the refraction of light rays corrects this visual
  disturbance

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Hyperopia Far Sighted
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Myopia

• Nearsightedness caused by a long eyeball. The
  cornea bends the light rays too sharply so the
  focal point of the light is in front of the
  retina
• Distant objects appear blurred and may appear
  clear only if the object is brought near the eye
  (can only see things that are near to you)
• Treatment a concave lens is used

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Myopia-Near Sighted
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Astigmatism

• This is due to the irregularity in the curvature
  of the cornea or the lens therefore, light rays
  are incorrectly bent causing blurred vision. A
  person usually has myopia or hyperopia along with
  astigmatism
• Treatment corrective lenses are required. These
  people have difficulty wearing contacts at times.
  Today, surgical procedures such as refractive
  surgery can be used to correct near or
  farsightedness. The cornea is reshaped to change
  the refractive angle of light as it passes through

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Nystagmus

• Constant, involuntary cyclical movement of the
  eye balls.
• Similar to spasms of the eyeball
• Ill show you ?

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Glaucoma

• Excess pressure of the aqueous humor. The blood
  constantly produces fluid that circulates in the
  eye and then gets reabsorbed into the
  bloodstream. Interference with the normal
  reentry of this fluid into the bloodstream leads
  to increased pressure inside the eyeball
• This condition occurs slowly, optic nerve damage
  occurs and poor vision is noticed

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Glaucoma
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Normal
Mild Glaucoma
Severe Glaucoma
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Cataracts

• Is an opacity of the lens or the outer covering
  of the lens
• Early cataracts causes a gradual loss of
  sharpness or (visual acuity). Untreated
  cataracts complete loss of vision
• Surgical removal of the lens and placement of an
  artificial lens is successful.
• Age, diabetes and exposure to UV rays may cause
  cataracts

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Cataract
Normal

• Cataract

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Caracts
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Diabetic Retinopathy

• The retina is damaged by blood vessel hemorrhages
  and growth of new vessels. Blood vessels in the
  eye are tiny and get filled with plaque or too
  much sugar d/t uncontrolled diabetes and they
  tear away from the retina and eyeball. Blindness
  can occur

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Diabetic Retinopathy
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Retinal Detachment

• The retina becomes separated from the underlying
  layer of the eye as a result of trauma or an
  accumulation of fluid or tissue between layers.
  Can occur slowly or suddenly. If left untreated,
  blindness will occur d/t total detachment of
  retina
• Surgery includes a spot welding with electric
  current or a weak laser beam. A series of
  pinpoint scars (connective tissue) develops to
  reattach the retina. Pt must lay face down for
  up to 48 hours after surgery to heal

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Retinal Detachment
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Macular Degeneration

• The macula or yellow area of the retina that
  contains the fovea centralis, (the point of
  sharpest vision), changes or becomes distorted.
  Either material accumulates on the retina or
  abnormal blood vessels grow under the retina
  causing it to detach.
• Surgery may stop the growth of blood vessels and
  delay vision loss. Causes are smoking, exposure
  to sunlight, and high cholesterol diet, can be
  hereditary

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Macular Degeneration
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Severe Macular Degeneration
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Eye Drops used in the Ophthalmologist's office

• Class
• Mydriatics used to dilate the pupil for
  opthalmic exams
• Big word Big pupil
• The D in this word dilates
• Atropine eye drops

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Eye Drops used in the Ophthalmologist's office

• Miotics used to constrict the pupil
• Little word, little pupil
• Pilocarpine constricts the ciliary muscles and
  pupil to increase the aqueous humor outflow so it
  wont get stuck

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Ophthalmoscope

• A lighted instrument, one of the most important
  tools of the physician, used to examine the
  interior of the eye, including the lens, retina
  and optic nerve
• The ophthalmoscope is equipped with a rotating
  disc of lenses to permit the eye be examined at
  different depths and magnifications. This may be
  enhanced by drugs that dilate the pupil and
  enlarge the opening into the structures within
  the eye.

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Infections of the eye

• Earlier, we discussed conjunctivitis,
• Stye this is a localized purulent
  staphylococcal infection. Can occur at any age.
  Causes redness, swelling, pain and formation of
  an abscess.
• Treatment warm compresses 4xs /day to help drain
  pus, topical ointment or antibiotic eye drop.
  Styes are contagious

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Infections of the eye

• Trachoma caused by the STD chlamydia, forms
  granules on the eyelid and irritates the cornea,
  causing blindness. Proper hygiene and
  antibiotics are used to treat this

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Opthalmia Neonatorum

• Caused by gonococcus, Chlamydia or some other
  STD, seen at birth. Instilling erythromycin eye
  drops after delivery rids this

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Injury to the eye

• The most common injury to the eye is related to a
  laceration or a scratching of the cornea caused
  by a foreign object
• Scar formation from the laceration or scratch
  causes an area of opacity through which light
  rays cannot pass. If the injury involves the
  central area in front of the pupil, blindness may
  result

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Preventing lacerations

• It is important to prevent injury, scratching or
  trauma to the eye. Even a tiny scratch can
  become so seriously infected that blindness can
  result
• Protection by using goggles has decreased severe
  eye injuries

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Enucleation

• An operation to remove the eyeball due to
  traumatic injury to the eye

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The End of the Eye lecture
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THE EAR
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THE EAR

• The ear is a sense organ for both
• Hearing
• And
• Equilibrium

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Otoscope

• A device for examination of the inner ear

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The ear is divided into 3 main sections

• 1. Outer ear
• 2. Middle ear
• 3. Inner ear

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The Outer Ear

• This includes the outer projection (pinna) or
  (auricle) of the actual ear and a canal
• The pinna collects and directs sound waves into
  the ear

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External auditory canal or meatus

• Once you enter the hole to the ear, you enter
  this external auditory meatus.
• Here, the skin lining this tube extends
  approximately 2.5 cm or more. There are many
  ceruminous glands here where cerumen is made
• This is where you stick a Q-tip to clean the ear

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At the end of this auditory meatus is

• The tympanic membrane A.K.A. the ear drum
• The ear drum serves as a boundary between the
  external auditory canal and the middle ear cavity
  and pressure on either side of this tympanic
  membrane is usually
• The tympanic membrane vibrates freely as sound
  waves enter the ear
• The tympanic membrane is usually pink or peach in
  color when not infected

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The Middle Ear

• This is the air space containing 3 small bones
  called ossicles
• These 3 ossicles are joined in such a way that
  they amplify the sound waves received by the
  tympanic membrane and then transmit the sounds to
  the fluid in the inner ear

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The 3 Ossicles are named individually

• 1. Malleus has a handlelike part that is
  attached to the tympanic membrane. The headlike
  part of the malleus bone is attached to the incus
• 2. Incus the middle of the 3 ossicles, attaches
  the malleus and the stapes. Sometimes called
  anvil
• 3. Stapes the innermost of the ossicles that is
  shaped like a stirrup. The base of the stapes is
  in contact with a membrane called the oval window
  of the inner ear. This membrane vibrates and
  transmits the sound waves to the fluid of the
  inner ear

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The Eustachian Tube

• Is an auditory tube that connects the middle ear
  to the throat or pharynx
• This tube opens to allow pressure to equalize on
  the two sides of the tympanic membrane
• The valve that closes the tube can be forced open
  by swallowing hard, yawning, or blowing with the
  mouth sealed as is done when one has pressure
  changes while being on an airplane

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Infections in the eustachian tube

• The mucuous membrane of the pharynx is continuous
  through the eustachian tube into the middle ear
  cavity, and organisms may travel along the
  membrane causing infection of the middle ear
  known as otitis media

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The inner ear

• This is the most complex of the 3 sections
• The inner ear contains the sensory receptors for
  hearing and equilibrium and contains fluid
  through which the vibratory sounds travel

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The Inner ear is complex

• The inner ear is complicated because it contains
  a mazelike area with 3 divisions
• 1. vestibule
• 2. Semicircular canals
• 3. Cochlear
• All 3 divisions contain fluid that are important
  to the sensory functions of the inner ear

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Hearing

• The organ of hearing is called the organ of
  corti. It consists of ciliated receptor cells
  located inside the cochlear or cochlear duct

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Hearing

• Sound waves enter the external auditory canal and
  cause the tympanic membrane to vibrate
• These vibrations are amplified by the ossicles
  and transmitted to the fluid of the inner ear
• The sound waves enter the upper chamber of the
  cochlea called the vestibular duct, and travel to
  the top of the duct
• As the fluid moves through these chambers, they
  set up vibrations in the fluid of the cochlear
  duct
• These vibrations stimulate the tiny, hairlike
  cilia on the receptor cells setting up nerve
  impulses that travel to the brain in the cochlear
  nerve (a branch of the 8th cranial nerve)

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Equilibrium

• Takes place in the semicircular canals in the
  inner ear.
• The semicircular canal contains sensory cells
• Receptors for the sense of equilibrium are
  ciliated cells. As the head moves, the delicate
  hair like cells bend when the liquid is set in
  motion by the head and body movements and a nerve
  impulse is generated. The nerve impulses are
  sent to the brain to help maintain body balance
  or equilibrium.
• The semicircular canals have nothing to do with
  the sense of hearing

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Ear Disorders

• Otitis Media
• Otitis Externa
• Otosclerosis
• Presbycusis
• Conduction deafness

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Otitis Media

• An infection of the middle ear cavity caused by a
  variety of bacteria or viruses
• Happens most often in children due to their ear
  canal being more horizontal, fluid sits there and
  causes bacteria to form
• Antibiotics are used to treat Otitis Media

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EAR DROPS

• In children lt3 years old, pull auricle/pinna down
  and back and place drop in ear. Because their
  ear canal is more horizontal, youll be sure to
  get the drop into the canal
• In children 3 years old/adults, pull
  auricle/pinna up and back d/t ear canal being sl.
  angled

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Myringotomy

• Pressure from pus or exudate in the middle ear
  can be relieved only by cutting the tympanic
  membrane (myringotomy) and then the placement of
  ear tubes to allow pressure to equalize and
  prevent further damage to the eardrum

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Otitis Media

• What treatments would be used for this problem

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Myringotomy
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Otitis Externa Swimmers Ear

• Inflammation of the skin of
• the external ear canal and
• auricle
• May be acute or chronic
• Most common in the summer
• Treatment is over 7 days with antibiotic drops,
  no swimming and possibility of wearing ear plugs
  with further swimming

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Conductive Hearing Loss

• This is when there is interference with the
  passage of sound waves from the outside to the
  inner ear
• There may be an obstruction of the external canal
  caused by wax or a foreign object
• Blockage of the eustachian tube prevents the
  equalization of air pressure on both sides of the
  tympanic membrane thereby decreasing the ability
  of the membrane to vibrate

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Otosclerosis

• A hereditary disease that
• causes bone changes in
• the stapes that prevents
• normal vibration
• Treatment surgical removal of the diseased
  stapes and its replacement with an artificial
  device allows conduction of sound from the
  ossicles to the oval window and the cochlea

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Presbycusis (pres-be-KU-sis)

• A slowly progressive hearing loss that often
  accompanies aging
• The condition involves gradual atrophy of the
  sensory receptors and the nerve fibers in the
  cochlear nerves

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Hearing Loss

• Affected person may feel isolated and depressed,
  psychological help may be needed
• The ability to hear high pitched sounds may be
  lost first
• It is therefore important to address elderly
  people in clear, low-pitched tones

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Hard of Hearing Sign

• H.O.H.
• Your hospital floor may have pre-made signs
  indicating that a pt has a hearing loss

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Nerve deafness

• Disorder of the cochlear nerve or auditory
  portion of the brain
• Nerve deafness may be caused by prolonged
  exposure to noise, drugs or infection

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The End