EYE AND EAR ASSESSMENT AND PROCEDURES

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CHAPTER 6

• EYE AND EAR ASSESSMENTAND PROCEDURES

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Introduction to Eye and Ear Assessment

• MA is responsible for performing a variety of eye
  and ear assessments and procedures
• Visual acuity test screening test to detect
  deficiencies in vision
• Hearing test use of tuning fork or audiometer
• Audiometer instrument that emits sound waves at
  various frequencies
• Color vision assessment requires specially
  prepared colored plates
• Color blindness inability to distinguish certain
  colors (Red and green most common)

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Structure of the Eye

• Eye has three layers
• Sclera outer layer
• Composed of tough, white, fibrous connective
  tissue
• Front of sclera is modified to form cornea
• Cornea transparent covering over the colored
  part of the eye

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Structure of the Eye, cont.

• Choroid middle layer
• Composed of many blood vessels and is highly
  pigmented
• Blood vessels nourish the eye
• Pigment absorbs stray light rays
• Front part of choroid specialized into
• Ciliary body muscles that control shape of the
  lens
• Suspensory ligaments suspend lens in place
• Lens focuses light rays on the retina
• Iris colored part of the eye controls size of
  the pupil
• Pupil opening in the eye that permits entrance
  of light rays

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Structure of the Eye, cont.

• Retina inner layer
• Light rays come to a focus on the retina
• Transmitted to brain by optic nerve to be
  interpreted
• Photoreceptors called rods and cones pick up
  different shades of light.

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Chambers of the eye

• Anterior chamber area between cornea and iris
• Posterior chamber area between iris and lens
• Aqueous humor fills both anterior and posterior
  chambers
• Vitreous humor transparent jellylike material
• Fills eyeball between lens and retina
• Function maintains the shape of the eyeball
• Conjunctiva membrane that lines eyelids and
  covers front of the eye, except for the cornea
• Conjunctiva covering the sclera is transparent
• Allows white sclera to show through

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Visual Acuity

• Visual acuity acuteness or sharpness of vision
• Normal visual acuity
• Can see clearly
• Able to distinguish fine details
• Both close up and at a distance

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Errors of Refraction

• Errors of refraction most common cause of
  defects in visual acuity
• Refraction bending of the parallel light rays
  coming into the eye so they can be focused on the
  retina

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Errors of Refraction, cont.

• Error of refraction light rays are not being
  bent properly
• Are not focused on retina adequately
• Cause defect in the shape of eyeball
• Can be improved with corrective lenses

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Myopia

• Myopia (nearsighted) eyeball too long from front
  to back
• Causes light rays to focus in front of retina
• Difficulty seeing objects at a distance
• May squint and have HA from eye strain
• Corrective lenses (eyeglasses, contact lenses)
  or laser surgery can correct condition

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Hyperopia

• Hyperopia (farsighted) eyeball too short from
  front to back
• Causes light rays to focus behind the retina
• Difficulty viewing objects that are close
• May have blurring, headache, and eye strain while
  performing close-up tasks
• Corrective lenses can correct condition

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Presbyopia

• Presbyopia decrease in elasticity of lens
• Usually begins after age 40
• Results in a decreased ability to focus clearly
  on close objects

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Eye Specialists

• Types of eye specialists
• Ophthalmologist specialist in dx and txof
  diseases and disorders of the eye
• Prescribes ophthalmic and systemic medications
• Performs eye surgery
• Optometrist licensed primary health care
  provider who has expertise in measuring visual
  acuity and prescribing corrective lenses
• Can dx and treat of disorders and diseases of the
  eye
• Prescribes ophthalmic medications but cannot
  prescribe systemic medications or perform eye
  surgery
• Optician professional who interprets and fills
  prescription for eyeglasses and contact lenses

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Assessment of Distance Visual Acuity (DVA)

• Used to diagnose myopia
• Along with other tests
• Snellen eye chart most often used
• Types of charts
• Letters in decreasing sizes (school-aged/adults)
• Capital letter E in decreasing sizes/different
  directions(preschool children, non-English-speakin
  g people, nonreaders)
• Pictures of familiar objects (preschoolers)

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Conducting a Snellen Test

• Perform in a well-lit room free from distractions
• Performed at a distance of 20 feet
• Two numbers next to each row of letters
• Number above line distance at which test is
  conducted (20 feet)
• Number below line distance from which a person
  with normal visual acuity can read the row of
  letters
• Normal DVA 20/20
• Person can read what supposed to read at 20 feet

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Conducting a Snellen Test, cont.

• DVA 20/30
• Smallest line the individual could read at 20
  feet
• People with normal acuity can read this line at
  30 feet
• DVA 20/15
• Smallest line the individual could read at 20
  feet
• Indicates above-average DVA
• People with normal acuity can read at 15 feet

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Conducting a Snellen Test, cont.

• Acuity of each eye measured separately
• Traditionally beginning with right eye
• If patient wears eyeglasses or contact lenses
  (except reading glasses)
• Keep them on during test
• Record in chart that corrective lenses were/were
  not worn

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Conducting a Snellen Test, cont.

• Eye occluder held over eye not being tested
• Patient's hand should not be used may encourage
  peaking through fingers
• Instruct patient to leave eye not being tested
  open
• Closing eye causes squinting of eye being tested

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Conducting a Snellen Test, cont.
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Snellen Eye Chart
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Snellen Big E Chart
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Assessment of Near Visual Acuity (NVA)

• Assesses patient's ability to read objects close
  up
• Used to detect hyperopia and presbyopia
• NVA card contains different sizes of type
• Ranging from size of newspaper headline down to
  very small print

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Assessment of Near Visual Acuity (NVA)

• Available in variety of forms
• Printed paragraphs
• Printed words
• Pictures

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Performing NVA Testing

• Perform test in well-lit room free of
  distractions
• Patient holds card at a distance of 14 to 16
  inches
• Reading glasses should be worn (if applicable)
• Each eye tested separately
• Eye occluder held over eye not being tested
• Instruct patient to keep covered eye open
• Patient asked to read each line or paragraph

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Assessment of Near Visual Acuity (NVA), cont.

• Observe patient for unusual symptoms
• Squinting, tilting of head, watering of eyes
• Patient continues until reaching smallest line
  that can be read
• Record results as smallest type patient could
  read with each eye
• Also record
• Date and time
• If corrective lenses worn
• Unusual symptoms exhibited by patient

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Near Visual Acuity Chart
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Assessment of Color Vision

• Classification of defects in color vision
• Congenital defect most common
• Inherited (present at birth)
• Most often affects males
• Acquired defect acquired after birth
• Eye injury
• Disease
• Certain drugs

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Assessment of Color Vision, cont.

• Color vision tests detect congenital color vision
  defects
• Often performed in medical office
• Basic color vision screening test
• Ask patient to identify red and green lines on
  Snellen chart

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Ishihara Test

• Detects
• Total congenital color blindness
• Red-green color blindness
• Series of plates colored dots forming a numeral
  against a background of dots of contrasting
  colors
• Patients with normal color vision can read
  appropriate numeral
• Patients with defects read dots as
• Not forming a number at all or forming a
  different number

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Ishihara Color Plates
From Ishihara J Tests for color blindness,
Tokyo, 1920, Kanehara.
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Ishihara Test, cont.
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Eye Irrigation

• Washing the eye with a flowing solution
• Purpose
• Cleanse the eye by washing away
• Foreign particles
• Ocular discharges
• Harmful chemicals
• Relieve inflammation though application of heat
• Apply an antiseptic solution

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Eye Instillation

• Dropping of a liquid into lower conjunctival sac
• Purpose
• Treat eye infections (with medications)
• Soothe an irritated eye
• Dilate the pupil
• Anesthetize during eye examination or treatment

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Structures of the Ear

• Functions in hearing and maintaining equilibrium
• Consists of three divisions
• External ear
• Auricle (pinna) flap of cartilage covered with
  skin that receives and collects sound waves and
  directs them toward the external auditory canal
• External auditory canal extends from auricle to
  tympanic membrane (aka external ear canal)
• Lined with skin that contains nerve endings, fine
  hairs, glands
• Glands secrete cerumen lubricates and protects
  ear canal

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Structure of the Ear, cont.

• Canal has an S-shaped curve as it leads inward
• Canal must be straightened during
• Tympanic membrane located at end of the canal
• Pearly gray semitransparent membrane
• Receives sound waves

1. Otoscopic examination
2. Ear instillation
3. Ear irrigation
4. Aural temperature measurement

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Structure of the Ear, cont.
From Applegate EJ The anatomy and physiology
learning system, ed 2, Philadelphia, 2000,
Saunders.
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Structure of the Ear, cont.

• Middle ear air-filled cavity
• Contains three small bones (ossicles) Malleus,
  Incus, Stapes
• Eustachian tube connects middle ear to the
  nasopharynx
• Stabilizes air pressure between the external
  atmosphere and the middle ear
• Inner ear
• Cochlea essential organ of hearing
• Semicircular canals maintain equilibrium

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Assessment of Hearing Acuity

• Part of complete PE
• Person can have hearing loss and not be aware of
  it
• Early detection and treatment may prevent
  permanent hearing loss
• Person with normal hearing can hear frequencies
  of normal speech
• Ranges from 300 to 4000 Hz (hertz or cycles per
  second)
• Patients who exhibit hearing loss
• a. Referred to otolaryngologist or
  audiologist

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Conductive Hearing Loss

• Conductive hearing loss results when there is a
  physical interference with normal conduction of
  sound waves through external and middle ear
• Most common type of hearing loss
• Amount of sound reaching inner ear is less than
  normal
• c. Cause of conductive loss often detected by
  examining the ear canal with otoscope
• Hearing frequently restored by
• Removing obstruction (e.g., cerumen)
• Treating the disorder (e.g., serous otitis media)

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Sensorineural Hearing Loss

• Sensorineural hearing loss results from damage
  to inner ear or auditory nerve
• Causes
• Hereditary factors
• Intense noise exposure over period of time
• Tumors
• Changes from normal aging process
• Ototoxicity caused by certain medications
• Infectious diseases (measles, mumps, meningitis)
• Mixed hearing loss combination of both
  conductive and sensorineural loss

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Hearing Acuity Tests

• Include
• Simple gross screening test
• Qualitative tests tuning fork
• Highly sensitive tests audiometry
• Important to test only one ear at a time
• Hearing deficit may exist only in one ear
• Ear not being tested blocked by an earplug or
  masked
• Masking presentation of sound to ear not being
  tested

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Gross Screening Test

• Gross Screening Test
• Used to identify a very large hearing impairment
• Whisper test patient asked to repeat simple word
  or series of numbers
• Whispered from a distance of 1 to 2 feet

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Tuning Fork Tests

• Tuning Fork Tests
• Provide a general assessment of hearing acuity
• Use of tuning fork with frequency of 512 or 1024
  Hz
• These frequencies fall within range of normal
  speech

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Audiometry

• Measurement of hearing acuity using an audiometer
• Audiometer an instrument that quantitatively
  measures the various frequencies of sound waves
• Provides information on
• How extensive hearing loss is
• Which frequencies are involved

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Audiometry, cont.

• To perform test
• Conduct test in quiet room
• Headphones placed snugly over ears
• Each ear assessed separately
• Audiometer delivers a single frequency at a time
• Starts with low frequencies and goes to high
  frequencies
• Patient signals when sound is heard
• Results plotted on a graph (audiogram)

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Audiometry, cont.
Courtesy GSI Grayson-Stadler, Milford, NH
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Ear Irrigation

1. Washing of the external auditory canal with a
   flowing solution

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Ear Irrigation, cont.

• Performed to
• Cleanse external ear canal to remove cerumen,
  discharge or foreign body
• Relieve inflammation by applying antiseptic
  solution
• Apply heat to ear
• Impacted cerumen must be softened before removal
  by instilling warm mineral oil or hydrogen
  peroxide (10 to 15 minutes)
• Do not perform irrigation if tympanic membrane is
  perforated (middle ear infection could occur)

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Ear Instillation

• Dropping of a liquid into the external auditory
  canal
• 2. Performed to
• Soften impacted cerumen
• Combat infection with antibiotic eardrops
• Relieve pain