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Eye and Ear Diseases and Disorders 347
■ Etiology. Excessive pressure inside the eye occurs if
too much fluid is produced or does not drain properly.
There are several forms of glaucoma, including open
angle and closed-angle glaucoma.
■ Symptoms. Generally speaking, glaucoma progresses
slowly, might or might not be symptomatic, and rarely
affects individuals under age 40. Increased pressure
inside the eye for a continued period of time can lead
to damage of the optic nerve and blindness, and perma
nent damage is often done before symptoms occur. For
this reason, intraocular pressure should be checked on
an annual basis.
■ Diagnosis. Diagnosis is made on the basis of an
ophthalmic examination and tonometry revealing an
increase in intraocular pressure.
■ Treatment. Early treatment is essential to prevent
permanent blindness. Depending on the form of
glaucoma, treatment can include use of eye drops or
surgery. Both are directed toward either reducing the
amount of aqueous humor produced or improving the
drainage.
■ Prevention. Regular eye examination with monitor
ing of eye pressure to discover glaucoma before any
damage is done is the best preventive measure.
Nystagmus
■ Description. Nystagmus (nis-TAG-mus) is a constant,
involuntary movement of the eyes that might be unno
ticed by the affected individual. Movement can be verti
cal, horizontal, circular, or a combination of these. One
or both eyes might be affected.
■ Etiology. Nystagmus might be the result of brain
tumors, disease, alcohol abuse, or congenital defects.
Diseases that cause nystagmus include Meniere’s disease
and multiple sclerosis.
■ Symptoms. Abnormal eye movement as described.
■ Diagnosis. It is usually easy to diagnose nystagmus
but difficult to diagnose the cause. Computerized
tomography (CT) scan, magnetic resonance imaging
(MRI), myelogram, angiography, and spinal tap might
be needed to confirm the cause of the condition.
■ Treatment. Treatment is directed toward correction
of the underlying cause. Congenital nystagmus is often
untreatable and permanent.
■ Prevention. Prevention is aimed at curing or prevent
ing the cause.
Figure 16-13 Strabismus.
Strabismus
■ Description. Strabismus (strah-BIZ-mus) is a disorder
in which the eyes fail to look in the same direction at the
same time (Figure 16-13). Strabismus is often incorrectly
referred to as lazy eye and as crossed eye or cockeye.
■ Etiology. Strabismus is the result of muscle weak
ness in one or both eyes. The affected eye can deviate
upward or downward, but more commonly, it looks
inward (convergent strabismus) or outward (divergent
strabismus). Strabismus commonly occurs in children
and requires early intervention to prevent amblyopia
(AM-blee-OH-pee-ah), a decrease in the vision of the
affected eye due to a lack of visual stimuli.
■ Symptoms. The primary symptoms of strabismus
are diplopia (dih-PLOH-pee-ah), or double vision, and
altered eye movement.
■ Diagnosis. A cover test is helpful in diagnosis. This
involves covering each of the eyes while the individual
is looking at an object. The straight eye will continue
to look at the object when the opposite eye is covered.
When the straight eye is covered, the strabismic eye will
shift or straighten to fixate on the object.
■ Treatment. Treatment often consists of covering
the normal eye in an effort to force the affected eye to
function. Eye exercises and corrective lenses also can be
ordered. The earlier the treatment is begun, the better.
If correction is not made by the age of 6 or 7, the visual
impairment can be permanent. Surgical intervention
might be needed to correct strabismus.
■ Prevention. Strabismus cannot be prevented, but
complications can be prevented with early detection
and proper treatment.
348 Chapter 1 6
Complementary and Alternative Therapy
Nutrition and Eye ew research studies on eye health and diet are demonstrating that certain foods
may help prevent the risk for glaucoma. Glaucoma is a condition of increased pres
eal
sure in the eye that causes degeneration of the retinal neurons that can lead to damage
to the optic nerve and blindness. Decreasing the intraocular pressure is the goal in treat
ment of glaucoma. There is some potential for using dietary changes to positively affect
the intraocular pressure and thus prevent the progression of glaucoma, but studies so far
have shown that proper nutrition may reduce the risk of glaucoma but not necessarily
the disease once it has progressed. It has been shown that a low intake of vitamin A and
omega-6 fats are associated with glaucoma risk as well as a high intake of iron and cal
cium. Caffeine is also a substance that may increase glaucoma risk but the amounts have
not been established. Dietary supplements have not been shown to reduce the risk of
glaucoma. Recommendations are to eat a diet high in antioxidants but further research
is necessary to demonstrate the benefit of dietary adjustments for glaucoma risk and
treatment.
Source: Wright (2020)
Macular Degeneration
■ Description. Macular degeneration is a degeneration
of the macular area of the retina, which is important in
seeing fine detail.
■ Etiology. The cause of this degeneration can be due
to the effects of drugs, but the most common cause
is aging. Risk factors include farsightedness, light eye
color, and cigarette smoking. This disease is the leading
cause of visual impairment in individuals 50 years of
age and older.
■ Symptoms. The primary symptom is a loss of cen
tral vision. Peripheral vision and color perception are
unaffected. The disease generally develops slowly and
painlessly, and both eyes are usually affected. As the
disease progresses, reading and activities that require
fine, detailed vision become impossible. There can be a
complete loss of central vision, but generally, blindness
does not occur.
■ Diagnosis. Diagnosis is made on the basis of fluores
cein angiography and routine examination.
■ Treatment. Vision might be improved in some cases
by laser surgery or by taking antioxidant vitamins.
There are also several new drugs on the market to treat
age-related macular degeneration, and the Food and
Drug Administration recently approved an implantable
miniature telescope.
■ Prevention. Since the most common cause is due to
aging, this condition cannot always be prevented. Some
activities aid prevention and include smoking cessation,
eating foods high in antioxidants, eating fish regularly,
wearing sunglasses that block ultraviolet light, manag
ing other diseases such as cardiovascular disease and
hypertension, and getting regular eye exams.
Diabetic Retinopathy
■ Description. Diabetic retinopathy (RET-ih-NOP-ah-
thee; retino 5 retina, opathy 5 disease) is a complica
tion of diabetes and the leading cause of blindness in
the United States. This condition can happen to any
individual with type 1 or type 2 diabetes. The longer
the individual has diabetes, the more likely is the devel
opment of diabetic retinopathy.
■ Etiology. Diabetes mellitus causes vascular changes
in the retina that lead to a decrease in visual acuity.
These changes include capillary aneurysms (also called
microaneurysms), microhemorrhages, venous dilation,
and new vessel growth (Figure 16-14). The affected
vessels tend to bleed easily into the retina and produce
scarring.
■ Symptoms. Retinal scarring decreases visual acu
ity and can ultimately cause permanent blindness.
These vascular changes tend to occur in both eyes
and are more extensive in uncontrolled diabetes or in
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Eye and Ear Diseases and Disorders 349
Healthy Highlight
Foods to Help Dry
Eyes
D
ry eye syndrome (DES) can be helped by using artificial tears, but also by eating
a healthy diet. Studies have shown that people with DES often have low levels of
omega-3 fatty acids in their food choices. Some of the foods that contain these include
walnuts, flaxseeds, beans, fish, olive oil, and winter squash. Other supplements that
help DES are the antioxidant vitamins C and E, agents that can be naturally found in
vegetables, fruits, and plants. Citrus fruits like oranges, grapefruit, and lemons are good
sources of vitamin C. Antioxidants are also synthesized in the body and are essential to
the immune system. They can be found in vegetables, fruits, legumes, and wholegrain
foods. Green tea is a good drink because it has antioxidants called catechins which also
have anti-inflammatory properties.
(A)
New vessel
formation
Microaneurysms
Microhemorrhages
Venous
dilation
Vascular retinopathies
(B)
Figure 16-14 Vascular changes caused by diabetic
retinopathy.
individuals whose blood sugar is not controlled. Dia
betic retinopathy can be asymptomatic in the early
stages, but as the disease progresses, symptoms include
blurred vision, poor night vision, floating spots in the
visual field, and vision loss.
■ Diagnosis. This condition is best diagnosed with a
dilated eye exam to allow the physician to see abnor
mal blood vessels, blood or fatty deposits in the retina,
retinal detachment, and damage to the nerve tissue, all
symptoms of diabetic retinopathy.
■ Treatment. Laser photocoagulation treatment is usu
ally effective, but the condition tends to recur and might
need repeated treatment.
■ Prevention. Prevention is directed toward con
trolling blood sugar levels to reduce the retinopathy.
Other preventive methods include monitoring and
controlling blood pressure and cholesterol levels,
not smoking, reducing stress, and getting regular eye
examinations.
Color Blindness or
Color Vision Deficiency
■ Description. Normal ability to see colors diminishes
with age due to the progressive yellowing of the lens.
Colors become less intense, and the colors of green
and blue often become more difficult to distinguish.
Difficulty in distinguishing colors also can occur in
young individuals affected with color vision deficiency
(CVD).
■ Etiology. Color blindness also commonly occurs as
an inherited, X-linked disorder that affects approxi
mately 1 in 10 males. It is rarely seen in females.
Figure 16-15 Ishihara color test plate. The numeral
“74” should be clearly visible to viewers with normal
color vision.
■ Symptoms. There are three main kinds of color
vision defects. Red-green color vision defects are the
most common, occur more often in men, and affect
the ability to distinguish between red and green. The
other major types are blue-yellow defects and complete
absence of color vision.
■ Diagnosis. CVD can be diagnosed using color plates
or charts. A common plate is the Ishihara color plate
shown in Figure 16-15.
■ Treatment. There is no known treatment or cure for
color blindness. Interestingly, affected individuals might
be sought to perform military duties that include the
discovery of camouflage. Color-blind individuals might
exhibit an uncanny ability to see through camouflage,
especially that using shades of green.
■ Prevention. There are no preventive measures.
Common Diseases of the Ear
The common diseases of the ear include infections and
conditions of decreased hearing or total hearing loss.
Gradual hearing loss can be due to a primary ear dis
order, such as an infection, or secondary to a disease
or injury.
Infection
The ear and related bony structures are commonly
subject to infection. The middle ear is connected to the
nasopharynx by way of the Eustachian tube, making it
easily accessible to bacteria that cause throat and respi
ratory infections. The external ear is open to the exter
nal environment, allowing infection from air and water.
The bony mastoid process connects with the middle ear
and is subject to infections affecting the middle ear. Ear
infections are more common in infants and children.
Consider This...
Wearing headphones or earplugs for an
hour increases the bacteria in an individu
al’s ear by 700 times.
Otitis Media
■ Description. Otitis media is inflammation in the mid
dle ear. It usually affects infants and young children and
is commonly called middle-ear infection, but it might
not necessarily be an infection. The middle ear is nor
mally filled with air, but when this area fills with fluid,
inflammation occurs. For this reason, otitis media is
classified by the type of fluid that fills the ear.
Serous
■ Etiology. The fluid is clear and can be due to a Eusta
chian tube obstruction, allergy, or change in middle-ear
pressure. Middle-ear pressure commonly occurs with
air flight. Any of these situations may allow clear serous
fluid to accumulate in the middle ear. This fluid accu
mulation causes inflammation of the middle ear, but
without infection.
■ Symptoms. Symptoms are usually mild and include a
feeling of fullness in the ear and conductive hearing loss.
Suppurative
■ Etiology. The fluid is pus due to a bacterial infection
in the middle ear. The suppurative (SUP-you-RAY-
tiv; formation of pus) form of otitis media is often due
to bacteria entering the middle ear, usually from the
Eustachian tube during an upper respiratory infection.
Blowing the nose forcefully often drives respiratory bac
teria through the Eustachian tube into the middle ear.
Swimming in contaminated water can be another cause
of suppurative infection.
■ Symptoms. Symptoms include varying degrees of
otalgia (oh-TAL-gee-ah; ot 5 ear, algia 5 pain), nausea,
vomiting, fever, chills, vertigo (VER-tih-go; dizziness),
and conductive hearing loss.
The structure and position of the Eustachian tube
is an important factor with either type of otitis media. If
the Eustachian tube is narrower, shorter, more horizon
tally placed than normal, or all three of these conditions,
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Eye and Ear Diseases and Disorders 351
Healthy Highlight
Some Drugs
Can Cause Ear
Problems
C
ertain drugs are called ototoxic, that is, they can cause damage to the ears. Antibi
otic medications are the most common ototoxic drugs. Gentamycin, streptomycin,
neomycin, and tobramycin are antibiotics that are known as ototoxic. Some chemo
therapy agents such as cisplatin and carboplatin as well as diuretics like furosemide
are also ototoxic. Even a few common over-the-counter medications like non-steroidal
anti-inflammatory agents can be harmful to the ears. A few herbal products are also
in this category. However, not all ototoxic drugs will cause ear problems in the user,
it is just wise to be aware of that possibility. There are many factors that will increase
chances of toxicity including how much of the medication was taken, for what length
of time the medication was taken, if the individual has a family history of ear problems,
and the number of ototoxic medications the individual is taking at the same time.
Symptoms of toxicity include tinnitus, hearing loss, dizziness or balance issues, and at
times, pain. If such symptoms appear, the individual is encouraged to see a health care
provider as soon as possible. Taking a list of all medications with dosages and times
taken to the health care visit is important.
Source: Lustig, L. (2020)
the individual is more prone to otitis media. Infants
and young children normally have narrower and more
horizontally placed Eustachian tubes, thus predispos
ing them to otitis media. As the child grows, the tube
becomes more vertical, which explains why children
often outgrow ear infections.
■ Diagnosis. Diagnosis is made on the basis of otos
copy revealing a bulging tympanic membrane or ear
drum (Figure 16-16). The normally pearly colored
tympanic membrane is red and swollen. If the tym
panic membrane is ruptured, a culture of the fluid can
be performed; otherwise, cultures are not obtainable.
An elevated white blood cell count is also indicative of
infection.
■ Treatment. Treatment for both types of otitis media
includes analgesics for pain and decongestants to pro
mote drainage. Suppurative otitis media requires anti
biotic therapy.
Chronic otitis media, both forms, might need
surgical removal of fluid by myringotomy (MIR-in-
GOT-oh-me; myringo 5 eardrum, otomy 5 incision
into) to prevent rupture of the tympanic membrane,
permanent hearing loss, and possible mastoiditis. To
prevent further accumulation of fluid and to relieve
pressure, tympanostomy (TIM-pan-OSS-toh-me;
tympano 5 eardrum, ostomy 5 new opening) tubes,
commonly called pediatric ear (PE) tubes, can be
placed through the tympanic membrane during a
procedure called a tympanoplasty (TIM-pah-no-
PLAS-tee; tympano 5 eardrum, plasty 5 surgical
repair) (Figure 16-17). Tubes commonly fall out
after several months but can be removed after six
months to a year. Prognosis for both types of otitis
media is good if given prompt treatment. Chronic
untreated otitis media, however, can lead to severe
ear damage and permanent hearing loss. Prevention
of complications is directed toward prevention and
prompt treatment of upper respiratory infections
and otitis media.
■ Prevention. Avoiding bottle feeding, smoking envi
ronments, and group child care are all preventive mea
sures. Babies who are breast-fed, cared for in their
homes, and kept in nonsmoking environments have
fewer bouts of otitis media.
Otitis Externa
■ Description. Otitis externa, also called swimmer’s ear
or external otitis, is an inflammation of the external ear
canal.
■ Etiology. This disease commonly affects swimmers
who spend many hours in the water. Other causes
include trauma to the ear canal, such as can occur when
attempting to scratch or clean the ear canal, and when
352 Chapter 1 6
(A)
Bulging membrane
Congested vessels
Bulging tympanic membrane
Normal
Figure 16-16 (A) Bulging tympanic membrane indicative of otitis media. (B) Bulging tympanic membrane.
swimming in contaminated water. The condition often
is due to bacterial or fungal infection. Wearing head-
phones/earphones/earbuds also creates a favorable envi
ronment for the growth of microorganisms.
■ Symptoms. Symptoms of otitis externa include an
inflamed ear canal with extreme pain, fever, pruritus
(proo-RYE-tus; itching), and hearing loss. The ear also
might drain clear or purulent (PYOU-roo-lent; con
taining pus) fluid.
■ Diagnosis. Diagnosis is made on the basis of an oto
logic examination. If an infection is suspected, a culture
and sensitivity test might be needed.
■ Treatment. Treatment includes keeping the ear canal
clean and dry and giving analgesics for pain and antibi
otics if an infection is detected.
■ Prevention. Prevention includes wearing earplugs
while showering or swimming to keep the external
canal clean and dry. Decreasing the amount of time
headphones/earphones/earbuds are worn and keeping
foreign objects out of the ears also can be helpful. Otitis
externa tends to be a recurring disease that can eventu
ally become chronic and cause hearing loss.
Mastoiditis
■ Description. Mastoiditis (MAS-toy-DYE-tis) is
inflammation of the mastoid bone or process. This
bone is porous or honeycombed in appearance and
located behind the ear (Figure 16-18). This condition
commonly affects children and is usually the result of a
middle-ear infection. Prior to antibiotics, this was
a leading cause of death in children. With current
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Eye and Ear Diseases and Disorders 353
Tympanic membrane incision
Tube placement
Tympanoplasty completed
Figure 16-17 Tympanoplasty.
Figure 16-18 Mastoiditis.
diagnosis and treatment regimens, it is less common
and rarely dangerous.
■ Etiology. Acute mastoiditis is usually the result of a
middle-ear infection commonly caused by Streptococcus.
■ Symptoms. Symptoms include tinnitus (tin-EYE-tus;
ringing in the ears), otalgia (oh-TAL-gee-ah; ot 5 ear,
algia 5 pain), fever, and headache. The mastoid also
can become swollen and painful, and ear drainage can
be present.
■ Diagnosis. Diagnosis is made on the basis of exam
ination and otoscopy (OH-TOS-koh-pee; oto 5 ear,
scopy 5 procedure to look into), X-ray of the mastoid
bone, CT scan, and bacterial cultures.
■ Treatment. Mastoiditis generally responds to antibi
otic therapy. Severe or chronic mastoiditis might need
354 Chapter 1 6
surgical treatment with a mastoidectomy (MAS-toy-
DECK-toh-me; mastoid 5 shaped like a nipple; refer
ring to mastoid process; ectomy 5 removal or excision)
to prevent complications and preserve hearing.
■ Prevention. Prompt and thorough treatment of ear
infections reduces the risk of developing mastoiditis.
Deafness
Deafness, or loss of hearing, is a common disease affect
ing millions of Americans. There are multiple reasons
for deafness, but most causes fall into two basic cate
gories: conductive and sensory. Conductive deafness is
caused by external or middle-ear disorders that decrease
or stop conduction of sound to the inner ear. Conduc
tive disorders include impacted cerumen, otosclerosis,
and a ruptured tympanic membrane. Sensory deafness
is the result of cochlear or auditory nerve damage that
impairs the ability of sound to be carried to the brain.
Sensory deafness is often related to damaging noise lev
els and ototoxic medications.
Impacted Cerumen
■ Definition. Cerumen is the soft, yellow-brown secre
tion produced by the external ear, commonly called ear
wax.
■ Etiology. Impacted cerumen is a common cause of
conductive hearing loss. If cerumen accumulates and
becomes impacted (pressed firmly) in the ear canal, it
can cause tinnitus and temporary deafness. An abnor
mal amount of cerumen can build up in the ear due to
skin dryness, excessive hair in the ear, or a narrow ear
canal. Another cause of buildup is due to excessive dust
in the ear, which occurs among construction workers,
farmers, and cabinetmakers, to name a few.
■ Symptoms. The common symptom is a partial loss
of hearing. Itching, tinnitus, and pain can also be
symptoms.
■ Diagnosis. An otologic examination will confirm the
diagnosis.
Healthy Highlight
Preserving and
Improving Your
Hearing
H
earing loss is a common problem for older adults, but in recent years it has
become a significant problem in younger populations. Good hearing is a global
priority. The World Health Organization is supporting public awareness activities
about hearing loss and preservation. Hearing loss costs billions annually and interferes
with the individual’s quality of life. Here are some tips to prevent hearing loss and to
help improve hearing.
■ Stay away from loud places. Exposure to noise should be below 85 decibels. Download
a phone app that registers the decibel level in your environment. Wear ear plugs at
noisy concerts or movies.
■ Wear good-quality ear protectors if shooting guns or working with high-level noise
equipment.
■ Use good-quality headphones and do not listen for more than 60 minutes per day at
about 60% of the maximum volume.
■ Be sure ears are clear and not clogged. Be careful when removing ear wax.
■ Use cupping to hear better if necessary, rather than turning up the volume.
■ If experiencing abnormal pain, swelling, or drainage, see a health care provider for
the proper diagnosis and treatment needed.
■ Read the side effects inserts for prescription medications. Many are ototoxic. Consult
with a health care provider if concerned about the side effects.
■ If necessary, see an audiologist for evaluation and proper hearing aid fitting or to find
out about other options to improve hearing.
Source: NIH (2020)
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Healthy Highlight
Removing Impacted
Cerumen
I
mpacted cerumen should be softened and removed gently in the following
manner.
1. Warm mineral oil or glycerin by holding it between the hands or placing the
bottle in a cup of warm water.
2. Check the temperature to ensure that it is not too hot. It should be lukewarm.
3. Drop two or three drops of oil in the ear canal.
4. Gently irrigate the ear canal by using a bulb syringe filled with lukewarm water.
5. Aim the water flow toward the top of the ear canal, not toward the eardrum.
6. Continue to irrigate until the impacted cerumen is removed. This can take 10
to 15 minutes.
7. Repeat steps 1-6 until the impacted cerumen is removed.
■ Treatment. Cerumen is normally washed out of
the ear during routine showering and shampooing.
Impacted cerumen is often removed with ear irriga
tions. This condition tends to recur, so routine exam
ination should be performed.
■ Prevention. Placing two to three drops of mineral oil
into the ear once a week, allowing it to remain for 3 to
4 minutes, and then rinsing it out with warm water is a
preventive method.
Otosclerosis
■ Description. Otosclerosis (OH-toh-skleh-ROH-sis;
oto 5 ear, scler 5 hardening, osis 5 condition) is a con
dition characterized by bony fixation of the small bones
of the middle ear. This fixation prevents the bones from
conducting vibrations from the eardrum to the inner
ear, causing a conductive hearing loss. Otosclerosis
occurs more commonly in women than in men; it usu
ally affects women under the age of 35 and can be aggra
vated by pregnancy.
■ Etiology. The cause of otosclerosis is unknown, but
there is evidence of familial tendency, suggesting a
hereditary cause.
■ Symptoms. The primary symptom is slow hearing
loss that continues to worsen.
■ Diagnosis. Diagnosis is made on the basis of physical
examination, audiogram, and otoscopy.
■ Treatment. A common treatment for otosclerosis is
a stapedectomy (STAY-peh-DECK-toh-me; stape 5
stapes, ectomy 5 removal or excision of). A stapedec
tomy involves removal of the stapes bone in the middle
ear and replacement with a prosthesis (pros-THEE-sis;
an artificial part) (Figure 16-19). Hearing is generally
Figure 16-19 Stapedectomy with wire prosthesis.
improved soon after surgery. If a stapedectomy is not an
option for the affected individual, a hearing aid might
improve hearing.
■ Prevention. Otosclerosis cannot be prevented.
Sensorineural Deafness
■ Description. Sensorineural deafness is a type of sensory
deafness due to damage to the cochlea or the auditory nerve.
■ Etiology. There are many causes of this condition;
some are congenital, or inherited, whereas others are
acquired. Acquired causes are more common and
include stroke, tumors, certain medications, infections,
diseases, and trauma. The most common trauma is due
to exposure to loud noise. Occupational noise, includ
ing that from heavy machinery, jackhammers, and air
plane engines, can lead to deafness. Teenagers and young
adults are at high risk due to the popularity of playing
loud music, especially while using personal ear buds, and
attending music concerts that use large amplifiers.
■ Symptoms. The primary symptom is a gradual loss
of hearing.
■ Diagnosis. Diagnosis is made on the basis of
audiometry.
■ Treatment. Sensorineural deafness caused by
cochlear or auditory nerve damage is often permanent.
Treatment is limited to use of hearing aids or cochlear
implants.
A hearing aid is a tiny microphone, amplifier, and
speaker in one device. It fits in the external ear and
increases volume to the internal ear.
A cochlear implant is an electronic device that is
implanted behind the ear. It directly stimulates the
auditory nerve fibers to increase hearing.
■ Prevention. Prevention is aimed at avoiding the cause
if possible. Reducing the amount of noise and protect
ing the ears by using protective earphones and earplugs
are beneficial.
Presbycusis
■ Description. Presbycusis (PRES-beh-KOO-sis; presby
5 old age, cusis 5 hearing) is a progressive sensory
hearing loss related to aging.
■ Etiology. The cause of presbycusis is from degenera
tive changes in the organs of hearing.
■ Symptoms. Onset of symptoms gradual and usually
begins after age 50. Initially, there is a loss of hearing of
high tones, but as hearing loss progresses, lower tones
become difficult to hear as well. In affected individuals,
the speech of others might seem mumbled or slurred,
and conversations might be difficult to hear, especially
against background noise.
■ Diagnosis. Diagnosis is made after physical exam
ination and medical history to rule out other causes of
hearing loss. An audiogram confirms the diagnosis.
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