0. Chapter 5 Diseases and Disorders of the Eye and Ear

1. Functioning Organs of Vision
Vision requires:
light stimulus
relay of light/image to the retina
stimulation of rods and cones in the retina
nerve impulses conducted to brain
Disorders of vision can occur with problems in any of these physiologic steps.
What are rods and cones and what is their function?

2. Normal Eye
Six extrinsic eye muscles control coordinated movements.

3. Functioning Organs of Vision (cont’d.)
Signs and symptoms that need medical attention:
visual disturbances
unequal pupils or sudden loss of vision
persistent pain
itching or burning in or around the eyes
Which eye disorders can be part of other systemic diseases?
What are some non-vision related symptoms that may indicate problems with the eye?

4. Functioning Organs of Vision (cont’d.)
Signs and symptoms that need medical attention
swollen, red eyelids
redness of the eyes
drainage or exudate
lesions/sores
involuntary eye movements
What type of visual disturbances or changes would require immediate medical attention?

5. Disorders of the Eye Refractive Errors Hyperopia (Farsightedness)
light focused behind the retina, which impairs near vision
Myopia (Nearsightedness)
light focused in front of the retina, which impairs far vision
What are some signs and symptoms of refractive errors?
Treatment requires fitting with artificial lenses (glasses, contact lenses) or surgical correction.
What is the eyeball shape in hyperopia?
What is the eyeball shape in myopia?

6. Disorders of the Eye Refractive Errors Astigmatism Presbyopia
light focused unevenly onto the retina, which causes blurred areas
Presbyopia
eye cannot focus quickly to accommodate changes in distance
In astigmatism, cornea is not spherical and light rays are diffused unevenly.
What is presbyopia?

7. Disorders of the Eye (cont’d.)
Nystagmus
involuntary, repetitive, rhythmic movements of one or both eyes
Strabismus
failure of the eyes to look together in the same direction
What causes Nystagmus?
Strabismus can develop in infancy or early childhood. By what age, if treated, is it reversible?
In adults, underlying conditions such as hypertension, diabetes, or head injury causes problems with eye muscles or related cranial nerves. Condition may or may not be correctable.

8. Disorders of the Eyelid (cont’d.)
Conjunctivitis
inflammation of the conjunctiva in one or both eyes
Mucous discharge from the eye
can be caused by viral or bacterial infection
highly contagious
commonly called “pink eye”
What are the conjunctiva? Where are they located?
May be treated with antibiotics or antiviral drugs, if severe. Usually, self-limited and resolves within 1-2 weeks.

9. Disorders of the Globe of the Eye
Cataracts
cloudy area in the lens
opacity blocks light from reaching retina
usually develop slowly
gradual reduction of vision
What causes cataracts?
What is the treatment to remove the cataract?

10. Disorders of the Globe of the Eye (cont’d.)
Glaucoma
damage to the optic nerve caused by elevated intraocular pressure
open-angle vs. closed-angle
One of the major cause of blindness
more common after age 60, but can occur at any age
more common with nearsightedness
What happens if glaucoma is left untreated?
What are symptoms of glaucoma?
Laser surgery is needed to create opening in the iris.

11. Disorders of the Globe of the Eye (cont’d.)
Macular Degeneration
progressive deterioration in retina
may start with mild distortion of central vision and progress to complete loss
usually both eyes are affected
leads to central vision blindness
Considered to be age-related. Genetic factors and exposure to bright light are also related.
Macular degeneration is the most common cause of blindness in the United States.
Is there a cure for macular degeneration?
What are treatments?

12. Disorders of the Globe of the Eye (cont’d.)
Diabetic Retinopathy
caused by small hemorrhages and newly formed vessels in the retina
decreased visual clarity
usually both eyes are affected
major cause of blindness
Occurs 8-10 years after onset of diabetes mellitus, especially those with poor glucose control.
What is the treatment for diabetic retinopathy?

13. Disorders of the Globe of the Eye (cont’d.)
Retinal Detachment
separation of the retina from the choroid
usually sudden and painless
early symptoms are seeing light flashes and floaters
more common with nearsightedness
results in blindness if untreated
Late symptom is dark shadow from periphery extending inward.
What causes the retina to detach?
Prompt surgical treatment is needed to reattach and prevent extension of tear.
Cryotherapy can be used to treat tears without detachment.

14. Chapter 5 Lesson 5.2

15. Functioning Organs of Hearing
Hearing requires:
vibratory or sound stimulus
relay of sound/vibration to inner ear
stimulation of tiny hairs in cochlea
nerve impulses conducted to brain
Besides hearing, what other functions do ears perform?
What types of problems would prevent the relay of sound from the outer ear to the inner ear?
Disorders of hearing can occur with problems in any of these physiologic steps.

16. Functioning Organs of Hearing (cont’d.)
Signs and symptoms that need medical attention:
hearing loss
ear pain or pressure
ringing or buzzing noise (tinnitus)
vertigo or dizziness
nausea and vomiting
What are some causes of hearing loss?
Many drugs or medications can cause hearing problems (e.g., aspirin, loop diuretics, chemotherapy agents).
Some environmental chemicals can cause permanent hearing loss (e.g., hexane, xylene).

17. Disorders of the Ear Disorders of Conduction impacted cerumen
infective otitis externa
swimmer’s ear
otitis media
otosclerosis
What is swimmer’s ear? Is it actually caused by swimming?
Otosclerosis is an abnormal bony growth in the middle ear.
Who does otosclerosis usually affect?

18. Disorders of the Ear (cont’d.)
Infective Otitis Externa
Inflammation of external ear canal with signs and symptoms of:
pain, often severe
red, swollen canal
fever
itching
drainage, watery or purulent
hearing loss
Can be caused cerumen accumulation, seborrhea, psoriasis, trauma to the ear canal.
What is the treatment of infective otitis externa?

19. Disorders of the Ear (cont’d.)
Otitis Media
Inflammation of the middle ear with signs and symptoms of:
feeling of fullness or pressure
impaired hearing
pain, often severe
drainage, watery or purulent
fever
nausea and vomiting
dizziness
Most common reason for visits to doctor by children.
What causes otitis?
Suppurative otitis is painful, and general symptoms of infection are present. It is caused by bacteria that enters through the nose, throat or ruptured tympanic membrane. Allergic response of the eustachian tube with swelling is sometimes responsible.

20. Disorders of the Ear (cont’d.)
Otitis Media
Treatment includes:
analgesics for pain relief
decongestants to promote drainage
antibiotics (for suppurative otitis)
myringotomy: surgical removal of the fluid in severe cases
Otoscope reveals inflamed tympanic membrane that may be bulging from fluid accumulation behind it.
Myringotomy tubes may be inserted to prevent fluid from reaccumulating.
Hypertrophied adenoids may need to be removed if condition becomes chronic.

21. Disorders of the Ear (cont’d.)
Ménière Disease
chronic disease of the inner ear
syndrome includes: vertigo, tinnitus, progressive hearing loss and sensation of pressure
sudden onset of episodes (vertigo, tinnitus, etc.)
duration of hours to days
treatment is symptomatic relief, not curative
What is the cause of Ménière disease?
Usually presents between years.
Nausea and vomiting, sweating, and loss of balance can accompany the vertigo.

22. Disorders of the Ear (cont’d.)
Labyrinthitis
inflammation of labyrinth usually from viral or bacterial infection; can result from meningitis
ruptured tympanic membrane
tear or injury resulting from pressure, untreated middle ear infection, force or trauma
What are the symptoms of labyrinthitis?
How do membranes get ruptured?
A tissue graft may be indicated, tympanoplasty, to repair the ruptured membrane.

23. Disorders of the Ear (cont’d.)
Sensorineural Hearing Loss
nerve impulses not transmitted to the brain due to damage to the cochlea or auditory nerve
hearing loss can result from loud music, industrial noise, nearby explosion, medications, the aging process, and certain other causes
irreversible, so prevention is essential
May occur spontaneously and suddenly or have a slow onset.
Why is it termed “occupational hearing loss?”
What is the treatment for sensorineural hearing loss?