Chapter 51: Sensory system function, data collection, and therapeutic measures: vision & hearing

Optometrist

(doctor of optometry) specializes in eye examinations to identify visual defects, diagnose problems, prescribe corrective lenses or other treatments, and refer for medical treatment

Inspection & palpation of the external ear

-. Inspection of the external ear begins with the auricle and the ear canal -A small bump on the inside of the helix (the upper external ear margin), Darwin's tubercle, is normal -The ear canal should be inspected before obtaining an infrared ear temperature because the presence of excess cerumen can alter the accuracy of the reading -To inspect the external ear canal, tip the adult patient's head toward the opposite side of the ear. Use a penlight or otoscope to inspect the canal -Next, the auricles and mastoid process are palpated. The mastoid process (bony prominence located behind the earlobe) should be smooth and hard, not tender or swollen.

Internal eye examination

-A dark room allows the pupil to dilate -Anticholinergic mydriatic eye drops that cause dilation may be used but are not always necessary. -the patient is asked to hold the head still while looking at a distant object. They are informed that the bright light could be uncomfortable. The HCP can examine the internal eye using a stationary device called a slit-lamp microscope -For this examination, the patient is seated and rests the chin on a support while a microscope and a bright light source are directed into the eye -Estimation of intraocular pressure is measured by using one of several types of tonometers

Punctal occulsion

-After eye drop administration, eyelids should be closed for 2 minutes without blinking, about the time it takes for absorption of the medication into the eye -The index finger is placed on the corner of the eye. Pressure is applied against the bone along the nose (not into the eye). This allows the eye drop to remain in the eye longer for greater effect. It also reduces systemic absorption and side effects.

Fluorescein and idocyanine green angiography

-Angiography with dye is a test using special cameras to find leaking or damaged blood vessels in retinal or deeper choroidal circulation -The patient is asked about prior dye reactions, then the pupil is dilated with intravenously injected dye that travels to the eye's circulation, making its blood vessels visible *Fluorescein is used for diabetic retinopathy and retinal vascular disease *Indocyanine green is used for the wet form of macular degeneration when blood is present.

Eye patching

-Apply ointment or drops if ordered and ask the patient to keep the eyelid shut -Place a disposable cotton gauze eye patch over the eye socket depression. -The patch is taped in place, and the patient is instructed to rest the eyes -Suggest quiet activities, such as listening to music or an audio book -Watching television or reading is not recommended because the patched eye will follow the movement of the unpatched eye.

Snellen chart

-E chart to measure distance acuity. A handheld visual acuity chart (Rosenbaum card) measures near acuity -has lines of letters labeled for visual acuity that range in size from the largest letters at the top to the smallest at the bottom -stand 20 feet from the chart -cover one eye and read aloud a line of letters. The lowest line (smallest letters) on the chart that the patient can read accurately designates the visual acuity of that eye *The E chart is used for people with literacy issues

Diagnostic eye test

-Exaudate culture -Digital imaging -Optical coherence tomography -Fluorescein & indocyanine green angiography -Electroretinography -Ultrasongraphy -Imaging tests

Inspection & palpation external structures

-Inspect size, shape & skin condition -Inspect external ear canal - note size for otoscope exam -Palpate external structure, including mastoid process, and pre-auricular & posterior auricular lymph nodes -Note any abnormal position of the ears, swelling, thickening, redness or tenderness

Structure of the eyeball

-Most of the eyeball is within the orbit, the bony socket that protects the eye from trauma -The six extrinsic muscles that move the eyeball are attached to the orbit and to the outer surface of the eyeball -Four rectus muscles move the eyeball side to side or up and down -Two oblique muscles rotate the eye. The cranial nerves that innervate these muscles are the oculomotor, trochlear, and abducens (third, fourth, and sixth cranial nerves, respectively

Visual fields

-Peripheral vision is the distance the eye sees objects up, down, right, and left while looking straight ahead

Weber tests

-Place the vibrating tuning fork on the center of the patient's forehead or head -Verify that the patient can hear the tuning fork -If the patient says yes, ask if they hear the sound better in the left ear, better in the right ear, or the same in both ears -Normally, the patient hears the sound the same in both ears

Outer & middle ear

-The outer ear consists of the auricle and the auditory canal -The middle ear is an air-filled cavity in the temporal bone -Vibrations of the tympanic membrane caused by sound are transmitted through the three auditory bones (ossicles). The stapes then transmits vibrations to the fluid-filled inner ear at the oval window.

Muscle baance & eye movement

-The patient looks straight ahead. The HCP moves their finger in the six cardinal fields of gaze, returning to the point of origin between each field of gaze -The patient follows the HCP's finger without moving the head. The purpose is to see if the patient's eyes can follow the HCP's finger in all fields of gaze without nystagmus, an involuntary, cyclical, rapid movement of the eyes. -corneal light reflex test checks muscle balance, conducted by shining a penlight toward the cornea while the patient stares at an object straight ahead. The light reflection should be at exactly the same place on both pupils. If eyes lack symmetry, muscle weakness could be present. -cover test is used along with an abnormal corneal light reflex test to evaluate eye muscle balance

Physiology of vision

-Vision involves the focusing of light rays on the retina and the transmission of the subsequent nerve impulses to the visual areas of the cerebral cortex. -The lens is the only adjustable part of the film -When the eye shifts focus to a nearby object, accommodation of the lens occurs -the pupil constricts in near vision to force photons through the thickness of the lens -Accommodation and pupil constriction increase the number of photons that strike the fovea centralis.

Physical examination of the eye consist of what?

-Visual acuity -Visual fields -Muscle balance & eye movenments -Pupillary reflexes -Inspection & palpation of external structures -Interenal eye examiination

Health history

-family history that can affect vision, including diabetes, hypertension, glaucoma, cataracts, and blindness -Patients are asked about general health status and disorders such as diabetes, hypertension, cancer, thyroid disorders, or rheumatoid arthritis -medication review checks for eye side effects -The patient is asked about eye symptoms or changes in visual acuity

Romberg test (falling test)

-instruct the patient to stand with feet together, first with eyes open and then with eyes closed -Normally, the patient has no difficulty maintaining a standing position with only minimal swaying -If the patient has difficulty maintaining balance or loses balance (a positive Romberg test), the patient may have an inner ear problem.

Inner ear

-is a cavity in the temporal bone called the bony labyrinth, lined with membranes called the membranous labyrinth -The fluid between bone and membrane is called perilymph, and fluid within the membrane is called endolymph -The structures of the bony labyrinth include the semicircular canals, vestibule, and cochlea

Pupillary reflexes

-pupils should be round, symmetrical, and reactive to light. To test pupillary response to light, both consensual and direct examinations should be completed. A slightly darkened room works best. The patient looks straight ahead, and the size of the pupil is noted. A penlight is shone toward the pupil from the side of the eye. Movement of the pupil is observed. The pupil should quickly constrict. The size of the pupil is noted when it constricts, known as direct response.

Rinne test

-strike the tuning fork and place it on the patient's mastoid process -Verify that the patient can hear the tuning fork, then instruct them to tell you immediately when they no longer hear the sound -Then, place the vibrating tuning fork 2 inches in front of the ear -Again, ask the patient whether they hear the tuning fork and to indicate when the sound stops -Normal findings are when the patient reports hearing the tuning fork when placed in front of the ear (AC) after it is no longer heard on the mastoid process (BC) *Normal results are recorded as "AC greater than BC."

Caloric test

-test the function of the eighth cranial nerve and assess vestibular reflexes of the inner ear that control balance -The test is not done if the ear canal is obstructed or the ear drum is perforate - The test is performed first on one ear and then the other. Warm (112°F [44.5°C]) or cold (86°F [30°C]) water is instilled into the ear canal *(Expected eye movements and nystagmus are noted. Dizziness may also be felt.

The process of hearimg involves

-transmission of vibrations and the generation of nerve impulses. When sound waves enter the auditory canal, vibrations are transmitted by the tympanic membrane, malleus, incus, stapes, oval window of the inner ear, perilymph and endolymph within the cochlea, and hair cells of the organ of Corti -When the hair cells bend, they generate impulses that are carried by the eighth cranial nerve to the brain. -The inner ear also has receptors for equilibrium -Dynamic equilibrium receptors are within the semicircular canals, whereas static equilibrium receptors are within the vestibule Within the utricle and saccule of the vestibule, the hair cells bend in response to gravity on the otoliths as the position of the head changes -The impulses generated are carried by the vestibular branch of the eighth cranial nerve to the cerebellum, medulla, and pons.

Electronystagmogram

-used to diagnose causes of unilateral hearing loss of unknown origin, vertigo, or ringing in the ears. -Contraindicated in clients with pacemakers -Usually tranquilizers, alcohol, stimulants, and antivertigo agents are avoided for 1 to 5 days before the test -The patient should also avoid tobacco and caffeine on the day of the test *The patient may experience nausea, vertigo, or weakness following the test.

Electroretinography

-used to diagnose diseases of the rods and cones -procedure evaluates differences in electrical potential between the cornea and retina in response to light wavelengths and intensity -The test is conducted with electrodes placed directly on the eye

The whisper voice test

Ask the patient to occlude one ear with a finger and push on the tragus to mask sound. Stand 1 to 2 feet away on the opposite side, behind the patient's field of vision, to prevent lip reading. Whisper two-syllable words toward the unoccluded ear, varying each whisper in volume. Ask the patient to restate the whispered words. Repeat the process on the other ear. Ask the patient if hearing was better in one ear than in the other ear. Normally, the patient should hear a soft whisper equally well in both ears. Findings of better hearing in one ear than the other or an inability to hear a soft whisper can indicate hearing impairment.

Sensory system data collection of the eye & visual status

Data collection of the eye begins with a subjective health history and objective observation, testing, and physical examination.

Tropia

Deviation of the eye away from the visual axis

Esotropia

Deviation toward the nose

Hypotropia

Downward deviation

Eye safety & injury prevention

Foreign objects Always wear safety goggles when working with tools or yard equipment. Chemical splashes Use splash shields around body fluids or chemicals. Close eyes to avoid getting hairspray in them. Corneal lens abrasions/infections from contact lenses Follow manufacturer's or eye care professional's directions for length of use and cleaning procedures. Do not wear contact lenses too long. Ultraviolet light (UV) Wear UV-protective sunglasses at all ages. Wear a hat to shield sun. Wear sunglasses with side shields after administration of mydriatics. Visual deficits Update prescription of glasses yearly. Wear glasses that fit properly, are clean, and are free of scratches. Computer vision syndrome (digital eye strain) Position the center of the computer screen 4 to 5 inches below eye level and the screen 20 to 28 inches from the eyes. Avoid glare on the computer screen. Blink frequently to prevent dry eyes. Rest eyes: Every 20 minutes, look 20 feet away for 20 seconds. Take a break every 2 hours for 15 minutes. Eye injury from sports Wear protective eyewear with polycarbonate lenses, facemasks, or helmets while participating in sports.

Nystagmus

Involuntary rapid eye movements

Arcus senilis

It is a gray, yellow, or white visible half-circles above and below the outer part of the cornea, the clear outer layer on the front of the eye.

Magnetic resonance imaging

MRI examines membranous organs, nerve, and blood vessels of the temporal bone for disease.

Extropia

Movement laterally

Optical Coherence Tomography (OCT)

Optical coherence tomography takes a picture of the retina. Light beams are shone into the eye at various angles. The amount of interference is measured, creating a detailed image of retinal depth.

Age related changes in hearing

Presbycusis is an age-related change in which progressive hearing loss is caused by loss of hair cells and decreased blood supplying the ear. This results in the loss of hearing high-pitched sounds (pitch = cycles per second; loudness = decibels). Because the ability to hear pitch, rather than volume, is lost, it is not helpful to talk louder to a patient with this type of hearing loss. In fact, talking louder can make it more difficult to discriminate sounds. Loss of high-pitched hearing causes the older adult to hear distracting background noises more clearly than conversation. It is important to know what helps a person hear best. Deafness or decreased hearing acuity is one of the main reasons that older adults withdraw from social activities. Older adults who have a hearing loss may need adaptive equipment in their home for safety. Using a hearing aid may increase hearing for those who do not have nerve damage deafness. The use of flashing lights instead of buzzers or alarms increases the safety of an older adult who is not able to hear a smoke detector or fire alarm.

Digital imaging

The instrument takes a digital picture of the retina in 2 seconds. Digital imaging assists in early detection of eye disease. A permanent photographic reference for the retina is obtained.

Tympanometry (Tests the movement of the tympanic membrane (ear drum) and evaluates middle ear function)

The tympanometer probe applies varying amounts of pressure to vibrate the tympanic membrane. The results are graphed on a tympanogram. The patient is informed that the tympanometry may cause transient vertigo. The patient is asked to report any nausea or dizziness felt during the test.

Consensual response

To conduct a consensual pupil examination, observe the eye just tested for reaction while shining the penlight into the other eye. The observed pupil should constrict

Imaging tests

X-ray films show bone structure and tumors -Computed tomography (CT) scan and magnetic resonance imaging (MRI) visualize ocular structures and abnormalities of the eye and surrounding tissues.

Cochlear implant

a microelectronic processor to convert sound into electrical signals, a transmission system to relay signals to the implanted parts, and a long, slender electrode placed in the cochlea to deliver the electrical stimuli directly to the fiber of the auditory nerve.

Opthalmologist

a physician who specializes in diagnosing and treating eye diseases

Hearing aid

an external amplifying device designed to improve hearing by more effective collection of sound into the ear

The optic disk may also be called what?

blind spot because no rods or cones are present

oculus uterque (OU)

both eyes

Cholesteatoma

cyst of epithelial cells and cholesterol found in the middle ear

Otorrhea

discharge from the ear

Ptosis

drooping of the eyelid

Ototoxic

drug that is damaging to the ear/hearing

Otalgia

ear pain

Eye tissue layers

fibrous, vascular, and neural

Readings above the normal range of 10 to 21 mm Hg may indicate what?

glaucoma

Opthalmoscope

handheld instrument with a light source. It magnifies the internal structures of the eye

Exudate Culture Eye Test

if exudate is present in any portion of the eye or around the eye, an exudate culture may be ordered to guide anti-infective treatment

Optician

is trained to grind and fit lenses prescribed by an ophthalmologist or optometrist

oculus sinister (OS)

left eye

Audiometric testing

measurement of hearing, usually with an instrument called an audiometer. the graphic representation of the results is called an audiogram

oculus dexter (OD)

right eye

Action of photoreceptorsterm-36

rods and cones

Accomodation

the ability of the pupil to respond to near and far distances

The wall of the eyeball has three layers, which are?

the outer fibrous tunic (sclera and cornea), the middle vascular tunic (choroid, ciliary body that suspends the lens, and iris), and the inner nervous tunic

Visual acuity

the sharpness of visual discrimination

What happens when protons strike the retina?

they stimulate chemical reactions in the rods and cones. Resultant changes generate a nerve impulse for transmission. Rods generate an action potential in dim light but only allow shades of gray vision. The cones are specialized to respond to a portion of the visible light spectrum; there are red-absorbing, blue-absorbing, and green-absorbing cone

ganglion cells of the eye

transmit the impulses generated by the rods and cones. These neurons all converge at the optic disc and pass through the wall of the eyeball as the optic nerve

Computed tomography scan (CT)

used to visualize the temporal and mastoid bones, the middle and inner ears, and the eustachian tube.

ultrasonography

useful when the internal eye cannot be visualized directly because of obstructions, such as corneal opacities or bloody vitreous. The eye is numbed with anesthetic drops. A transducer probe is placed on the eye to perform the ultrasound

How does optic neuritis occur?

vitamin B deficiency

Age related changes in vision

• Presbyopia, an inability to focus up close because of decreased elasticity in the ocular lens • Narrowing of the visual field and more difficulty with peripheral vision • Decreased pupil size and responsiveness to light • Difficulty with vision in dimly lit areas or at night (requires more light to see adequately) • Increased opacity of the lens, which causes sensitivity to glare, blurred vision, and interference with night vision • Yellowing of the lens, which reduces ability to differentiate low-tone colors of blues, greens, and violets (yellow, orange, and red hues are more clearly visible) • Distorted depth perception and difficulty correctly judging the height of curbs and steps • Decreased lacrimal secretions

Several types of hearing aids are commonly used today which are?

• The in-the-ear aid fits into the ear. • The behind-the-ear aid rests behind the ear and connects to the earmold in the ear canal by plastic tubing • The canal aid fits into the ear canal and is nearly unseen

Behaviors indicating hearing loss?

• Turns up volume on the television or radio. • Frequently asks, "What did you say?" • Leans forward or turns head to one side during conversations to hear better. • Cups hand around ear during conversation. • Says people are talking softly or mumbling. • Speaks in an unusually loud or quiet voice. • Answers questions inappropriately or not at all. • Has difficulty hearing high-frequency consonants. • Avoids group activities. • Shows loss of sense of humor. • Has strained or serious look on face during conversations. • Appears to ignore people or does not participate. • Is irritable or sensitive in interpersonal relations. • Reports ringing, buzzing, or roaring noise in ears