Chapter 5 Diseases and Disorders of the Eye and Ear

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?

Normal Eye Six extrinsic eye muscles control coordinated movements.

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?

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?

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?

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?

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.

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.

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?

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.

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?

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?

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.

Chapter 5 Lesson 5.2

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.

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).

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?

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?

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.

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.

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 40-50 years. Nausea and vomiting, sweating, and loss of balance can accompany the vertigo.

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.

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?