Chapter 11 · PDF file · 2016-04-05audit/o, ot/o Outer ear pinn/i Middle ear myring/o, tympan/o Inner ear labyrinth/o. Functions of Eyes •Receptor organs of sight •Receive images

Special Senses:

Eyes and Ears

Chapter 11

Related Combining Forms

Structure Related Combining Forms

Eyes opt/I, opt/o, optic/o,

ophthalm/o

Iris ir/i, ir/o, irid/o, irit/o

Lens phac/o, phak/o

Retina retin/o

Lacrimal apparatus dacryocyst/o, lacrim/o

Ears acous/o, acoust/o, audi/o,

audit/o, ot/o

Outer ear pinn/i

Middle ear myring/o, tympan/o

Inner ear labyrinth/o

Functions of Eyes

• Receptor organs of sight

• Receive images and transmit them to the

brain

Structures of the Eyes

• Eyeball

• Adnexa

Structures of Eyes

Adnexa of Eyes

• Structures outside the eyeball

– Orbit

– Eye muscles

– Eyelids

– Eyelashes

– Conjunctiva

– Lacrimal apparatus

Orbit

• Bony cavity of skull that contains and protects

the eyeball and associated muscles, blood

vessels, and nerves

Muscles of Eye

Muscles of Eye

• Six major eye muscles (three pairs)

– Superior and inferior oblique muscles

– Superior and inferior rectus muscles

– Lateral and medial rectus muscles

• Allow for wide range of precise eye

movements

Muscles of Eye

• Binocular vision

– Coordination of eye muscles allowing for

depth perception

• (bin-: two; ocul: eye)

• Depth perception

– Ability to see things in three dimensions

Eyelids, Eyebrows, and Eyelashes

• Provide protection from foreign matter,

excessive light, and injuries

• Canthus

– Angle where upper and lower eyelids meet

• (canth: corner of the eye)

• Cilia

– Small hair making up eyebrows/eyelashes

Eyelids, Eyebrows, and Eyelashes

• Tarsus

– Framework within upper and lower eyelids

providing necessary stiffness and shape

• (tars: edge of eyelid)

Conjunctiva

Conjunctiva

• Transparent mucous membrane lining

underside of the eyelid protecting the

exposed surface of the eyeball

Lacrimal Apparatus

• Structures producing, storing, and removing

tears

• Lacrimal glands

– Located on underside of upper eyelid just

above outer corner of each eye

• Lacrimal fluid

– Maintains moisture on the anterior surface of

eyeball

Lacrimal Apparatus

• Lacrimal canal

– Ducts at the inner corner of each eye

– Ducts collect tears emptying them into lacrimal sacs

• Lacrimal sac

– Enlargement of the upper portion of the lacrimal duct

• Lacrimal duct

– Passageway draining excess tears into nose

Eyeball

• One-inch sphere with only about 1/6th of its

surface visible

• Ocular

– Pertaining to the eye

• Extraocular

– Outside the eyeball

• Intraocular

– Within the eyeball

Walls of Eyeball

Walls of Eyeball

• Three layers

– Sclera

• White of the eye

• Maintains shape of eye

• Protects delicate inner layers of tissue

– Choroid

• Opaque middle layer of eyeball

• Provides blood supply to the entire eye

Walls of Eyeball

• Three layers

– Retina

• Innermost layer lining posterior segment of the eye

• Receives nerve impulses and transmits them to

the brain via optic nerve

Anterior Segment of Eyeball

Anterior Segment of Eyeball

• Anterior segment

– Front one-third of eyeball

– Located behind the cornea and in front of the

iris

– Aqueous humor helps maintain shape and

nourishes intraocular structures

– Intraocular pressure measures fluid pressure

inside the eye which is regulated by rate at

which aqueous humor enters/leaves the eye

Posterior Segment of Eyeball

• Posterior segment

– Remaining two-thirds of the eyeball

– Located behind the iris and in front of the

ligaments holding the lens in place

– Lined with the retina

– Filled with vitreous humor

– Fibers attached to the surface of retina help

maintain the shape of the eye

Structures of Retina

• Rods and cones

– Receive images that have passed through

lens

– Images convert into nerve impulses and

transmit to brain via optic nerve

– Rods

• Black and white receptors

– Cones

• Color receptors


• Macula

– Light-sensitive area in the center of the retina

– Responsible for sharp central vision

• Fovea centralis

– Pit in the middle of the macula

– High concentration of cones allows for the

best color vision


• Optic disk

– Where nerve endings of the retina enter optic

nerve

– Blind spot

– Contains no rods or cones

• Optic nerve

– Transmits nerve impulses from retina to the

brain

Uvea

• Pigmented layer of eye

• Rich blood supply

• Consists of choroid, ciliary body, and iris

Ciliary Body

• Set of muscles and suspensory ligaments

that adjust thickness of the lens and refine

the focus of light rays on retina

• Produces aqueous humor

• To focus on nearby objects, muscles adjust

the lens to make it thicker

• To focus on distant objects, muscles stretch

lens to make it thinner

Iris

• Colorful circular structure surrounding the

pupil

• Muscles control the amount of light entering

through the pupil

• Muscles contract allowing smaller opening to

decrease the amount of light entering eye

• Muscles relax allowing larger opening to

increase the amount of light entering eye

Cornea, Pupil, and Lens

• Cornea

– Transparent outer surface of eye covering iris

and pupil

– Focuses light rays entering the eye

• Pupil

– Black circular opening in the center of the iris

permitting light to enter the eye

Cornea, Pupil and Lens

• Lens

– Clear, flexible, curved structure contained

within clear capsule located behind the iris

and pupil

– Focuses images on the retina

Normal Action of Eyes

• Accommodation

– Eye adjustment for the vision at varying

distances

• Convergence

– Simultaneous inward movement of eyes

toward each other

– Allows maintenance of single binocular vision

as object comes nearer

Normal Action of Eyes

• Emmetropia

– Normal vision

• (emmetr: proper measure)

• Refraction

– Bending of light rays to focus on the retina

• Visual acuity

– Ability to distinguish object details and shape

at a distance

Medical Specialties Related to Eyes

• Ophthalmologist

– Specializes in diagnosing/treating

diseases/disorders of eyes

• (ophthalm: eye)

• Optometrist

– Provides diagnosis of eye diseases,

measuring accuracy of vision determining

need for corrective lenses

• (opt/o: vision)

Medical Specialties Related to Eyes

• Optician

– Health care practitioner who designs, fits, and

dispenses lenses for vision correction

Pathology of Eyes and Vision: Eyelids

• Ptosis

– Drooping of upper eyelid

• Chalazion

– Nodule or cyst related to obstruction in

sebaceous gland

• Blepharitis

– Swelling of eyelid, near eyelash follicles

• (blephar: eyelid)



• Ectropion

– Turning outward (eversion) of the edge of the

eyelid

• Entropion

– Turning inward (inversion) of the edge of the

eyelid

• Hordeolum

– Pus-filled lesion on the eyelid due to acute

infection in sebaceous gland


• Periorbital edema

– Swelling of tissue surrounding the eye(s)

• (peri-: around; orbit: eyeball)

– Associated with allergic reaction

Additional Adnexa Pathology

• Conjunctivitis

– Inflammation of conjunctiva usually due to

infection or allergy

– Pinkeye

• Dacryoadenitis

– Inflammation of lacrimal gland due to

bacterial, viral, or fungal infection

• (dacry/o: tear)

Additional Adnexa Pathology

• Subconjunctival hemorrhage

– Bleeding between conjunctiva and sclera

– Usually due to injury

• Xerophthalmia

– Dry eye due to decreased production of tears

by tear glands

– May be related to aging, systemic diseases or

Vitamin A deficiency

• (xer: dry)

Uvea, Cornea, Iris, and Sclera

• Uveitis

– Inflammation of uvea

• (uve: uvea)

• Iritis

– Form of uveitis affecting structures in the front

of the eye

• Corneal abrasion

– Injury to outer layers of cornea

• (corne: cornea)


• Corneal ulcer

– Pitting of cornea due to infection or injury

• Diabetic retinopathy

– Damage to retina as complication of

uncontrolled diabetes


• Keratitis

– Inflammation of cornea

– May be bacterial, viral, or fungal

• (kerat: cornea)

• Keratoconus

– Irregular, cone-shaped cornea leading to

distortion of vision


• Scleritis

– Inflammation of sclera

– May be associated with infections, chemical

injuries, or autoimmune diseases

• (scler: white of the eye)

Eye

• Anisocoria

– Unequal size of pupils

– May be congenital, or related to head injury,

aneurysm, or pathology of CNS

• (anis/o: unequal; cor: pupil)

• Cataract

– Loss of transparency of lens causing

progressive loss of visual clarity

Eye

• Floaters

– Particles of cellular debris in vitreous humor

casting shadows on the retina

– Occur normally

– May be an indication of retinal detachment

• Photopsia

– Appearance of flashes of light

• (phot: light; -opsia: view of)

Eye

• Miosis

– Contraction of pupil in response to light

– May be due to prescription or illegal drugs

• (mio: smaller)

• Mydriasis

– Dilation of pupil

– May be due to diseases, trauma, or drugs

• (midrias: dilation of pupil)

Eye

• Nystagmus

– Involuntary, constant, rhythmic movement of

eyeball

– Congenital, or due to neurological injury or

drug use

• Papilledema

– Swelling and inflammation of the optic nerve at

the point of entrance into eye through optic disk

• (papill: nipplelike)

Eye

Eye

• Retinal detachment

– Separation of some or all of the retina from

the choroid

– Lack of treatment leads to blindness

• Retinitis pigmentosa

– Progressive degeneration of retina affecting

night and peripheral vision

– Appears as dark pigmented spots on retina

Glaucoma

• Group of diseases characterized by

increased intraocular pressure resulting in

damage to the retinal nerve fibers and optic

nerve

• Open-angle glaucoma

– More common form

– Detected through regular eye examinations

– Asymptomatic until optic nerve is damaged

Glaucoma

• Closed-angle glaucoma

– Narrowing of area between cornea and iris

resulting in decreased fluid to trabecular

meshwork

– Sudden pain, nausea, redness of eye, and

blurred vision

– Lack of treatment leads to blindness in as little

as 2 days

Macular Degeneration

• Progressive condition causing damage to the

macula

• Results in the loss of central vision

– (macul: spot)

• Types:

– Age-related macular degeneration

– Dry macular degeneration

– Wet macular degeneration

Functional Defects

• Diplopia

– Perception of two images of a single object

• Hemianopia

– Blindness in one-half of the visual field

• (hemi-: half)

• Monochromatism

– Inability to distinguish certain colors

• (mon/o: one; chromat: color)

Functional Defects

• Nyctalopia

– Difficulty seeing at night, although normal

daytime vision

• (nyctal: night)

• Photophobia

– Excessive sensitivity to light

• (phot/o: light)

Functional Defects

• Presbyopia

– Decline of near vision related to aging

• (presby: old age)

Strabismus

• Improper eye alignment due to the inability of

eye muscles to coordinate

• Esotropia

– Inward deviation of one or both eyes

• (eso-: inward; trop: turn)

• Exotropia

– Outward deviation of one eye or both eyes

• (exo: outward)

Refractive Disorders

• Ametropia

– Images do not focus properly on retina

– Includes astigmatism, hyperopia, and myopia

• (ametr: out of proportion)

• Astigmatism

– Lack of focus due to uneven curvature of

cornea

Refractive Disorders

• Hyperopia

– Light rays focus beyond the retina

– Farsightedness

• Myopia

– Light rays focus in front of the retina

– Nearsightedness

Blindness

• Inability to see

• Legal blindness

– Best-corrected vision of 20/200

• Amblyopia

– Dimness of vision without any detectable

disease of eyes

• (ambly: dim or dull)

Blindness

• Scotoma

– Abnormal area of diminished vision

surrounded by area of normal vision

Diagnostic Procedures for Vision and Eyes

• Snellen chart

– Measures visual acuity

– Recorded as fraction with 20/20 representing

normal vision

• First number: standard distance from the chart

• Second number: deviation from the norm

• Refraction

– Determines refractive error

– Determines corrective lens prescription

Diagnostic Procedures for Vision and Eyes

• Diopter

– Unit of measurement of the lens' refractive

power

• Cover test

– Determines how eyes work together

– Assesses binocular vision

• Visual field testing

– Determines loss in peripheral vision

Diagnostic Procedures for Eyes

• Ophthalmoscopy

– Use of ophthalmoscope to visually examine

fundus of the eye

• Dilation

– Artificial enlargement of pupil to examine the

interior of the eyes

• Mydriatic drugs

– Force eyes to remain dilated in the presence

of bright light

Diagnostic Procedures for Eyes

• Slit-lamp ophthalmoscopy

– Focusing the beam of light onto parts of the eye

to permit examination of structures at front of

the eye such as the cornea, iris, and lens

• Fluorescein staining

– Application of fluorescent dye to the surface of

the eye via eye drops

– Causes corneal abrasion to appear bright green

Diagnostic Procedures of Eyes

• Fluorescein angiography

– Radiographic study of blood vessels in the

retina after injecting fluorescein dye

• PERRLA (Pupils are Equal, Round,

Responsive to Light and Accommodation)

– Diagnostic observation

– Abnormality could indicate head injury or

damage to the brain

Diagnostic Procedures of Eyes

• Tonometry

– Measurement of intraocular pressure

– Abnormally high pressure may indicate

glaucoma

• (ton/o: tension)

Treatment Procedures of Eyes and Vision

• Orbit and Eyelids

– Orbitotomy

• Surgical incision into orbit for biopsy, abscess

drainage, or removal of tumor/foreign object

– Tarsorrhaphy

• Partial or complete suturing together of upper and

lower eyelids when lids are paralyzed and unable

to close normally

– (tars/o: eyelid)


• Conjunctiva and Eyeball

– Corneal transplant

• Surgical replacement of scarred/diseased cornea

with clear corneal tissue from donor

– Enucleation

• Removal of eyeball, leaving the eye muscles intact

– (e-: out of; nucle: nucleus; -ation: action)

– Ocular prosthesis

• Artificial eye fitting over or replacing malformed

eye



– Iridectomy

• Surgical removal of a portion of the iris

– (irid: iris)

– Radial keratotomy

• Surgical treatment of myopia to bring focal point

closer to retina improving distance vision



– Scleral buckle

• Repairing of detached retina

– Vitrectomy

• Removal of vitreous humor and replacing with

clear solution

Cataract Surgery

• Lensectomy

– Surgical removal of cataract-clouded lens

• Phacoemulsification

– Ultrasonic vibration to shatter and remove

lens clouded by cataract

• Intraocular lens

– Surgically implanted replacement of natural

lens

Corrective Lenses

• Correct refractive errors

– Concave lenses

• Curved inward

• Used for myopia

– Convex lenses

• Curved outward

• Used for hyperopia

• May have two refractive powers (bifocal) or

three refractive powers (trifocal)

Corrective Lenses

• Contact lenses

– Float on tear film in front of eye

– Rigid gas-permeable lenses cover central part

of the cornea

– Disposable soft lenses cover entire cornea

Laser Treatments of Eyes

• Laser iridotomy

– Focused light beam is used to create a hole in

the iris

– Treatment of closed-angle glaucoma

• Laser trabeculoplasty

– Creates opening in the trabecular meshwork

allowing proper drainage of fluid


• LASIK (Laser-Assisted In Situ

Keratomileusis)

– Treats vision conditions caused by the shape

of cornea

• (-mileusis: carving)

• Photocoagulation

– Use of laser to treat some forms of wet

macular degeneration or to repair small retinal

tears


• Retinopexy

– Reattaches retinal detachment

Functions of Ear

• Receptor organ of hearing

• Receives sound impulses and transmit them

to the brain

• Inner ear helps maintain balance

• Auditory

– Pertaining to sense of hearing

• Acoustic

– Pertaining to sound or hearing

Structures of Ear

Structures of Ear

• Three separate regions

– Outer ear

– Middle ear

– Inner ear

Outer Ear

• Pinna

– Also known as auricle

– External portion of the ear

– Captures sound waves and transmits them

into external auditory canal

• External auditory canal

– Transmits sound waves to tympanic

membrane of the middle ear

Outer Ear

• Cerumen

– Earwax

– Secreted by ceruminous glands lining auditory

canal

– Protective substance that traps small insects,

dust, debris, and bacteria

Middle Ear

• Transmits sound across space between outer

ear and inner ear

• Tympanic

– Eardrum

– Located between outer and middle ear

– Membrane transmits sound by vibrating

• (Myring/o and tympan/o: tympanic membrane)

Middle Ear

• Mastoid process

– Temporal bone containing hollow air space

surrounding the middle ear

• Auditory Ossicles

– Transmit sound waves from eardrum to inner

ear by vibration

– Malleus (hammer)

– Incus (anvil)

– Stapes (stirrup)

Middle Ear

• Eustachian Tubes

– Lead from middle ear to nasal cavity and

throat

– Equalize air pressure within the middle ear

with that of the outside atmosphere

Inner Ear

• Contains sensory receptors for hearing and

balance

• Structures present in the inner ear are known

as labyrinth

• Oval window

– Located under the base of stapes

– Membrane separating the middle ear from the

inner ear

– Allows entrance of vibrations into inner ear

Inner Ear

• Cochlea

– Snail-shaped structure where sound

vibrations are converted into nerve impulses

– Contains cochlear duct, organ of Corti,

semicircular canals, and acoustic nerves

• Organ of Corti

– Relays vibrations to auditory nerve fibers that

transmit sound to the auditory center of the

cerebral cortex for interpretation

Inner Ear

• Semicircular canals

– Three

– Contain endolymph and sensitive hair cells

the bend in response to the movements of

head

– Assist with equilibrium

Inner Ear

• Acoustic nerves

– Transmit information to the brain

– Two parts

• Cochlear nerves transmit sound for hearing

• Vestibular nerves sense balance and head position

Normal Action of Ears

• Air conduction

– Process of sound waves entering the ear

through pinna and traveling down the external

auditory canal to strike tympanic membrane

• Bone conduction

– Occurs as eardrum vibrates causing auditory

ossicles to vibrate

Normal Action of Ears

• Sensorineural conduction

– Occurs when sound vibrations reach inner ear

– Structures receive sound waves and relay

them to the auditory nerve for transmission to

the brain

Medical Specialties Related to Ears

• Audiologist

– Specializes in measurement of hearing

function and in rehabilitation of persons with

hearing impairments

• (audi: hearing)

• Speech-language pathologist

– Assists patients with problems related to

swallowing, speech, and communication

disorders

Pathology of Ears and Hearing

• Outer ear

– Impacted cerumen

• Accumulation of earwax forming solid mass and

adhering to the walls of external auditory canal

– Otalgia

• Pain in the ear

– (ot: ear; -algia: pain)

– Otitis

• Inflammation of the ear


• Outer ear

– Otomycosis

• Fungal infection of the external auditory canal

– (myc: fungus)

– Otopyorrhea

• Flow of pus from the ear


• Outer ear

– Otorrhea

• Any discharge from the ear

– Otorrhagia

• Bleeding from the ear


• Middle ear

– Barotrauma

• Pressure-related ear condition caused by pressure

changes

– Cholesteatoma

• Epidermal cyst in middle ear and/or mastoid

process made of epithelial cells and cholesterol

– (cholesteat: cholesterol)


• Middle ear

– Mastoiditis

• Inflammation of any part of mastoid bone

– Infectious myringitis

• Contagious inflammation causing blisters on

eardrum

– Otitis media

• Inflammation of middle ear


• Middle ear

– Otosclerosis

• Ankylosis of bones of middle ear

• Results in conductive hearing loss

• Treatment: stapedectomy


• Inner ear

– Labyrinthitis

• Inflammation of labyrinth

• May result in vertigo and deafness

– Vertigo

• Sense of dizziness and loss of balance

– Benign paroxysmal positional vertigo

• Occurs with the shift in the location of the small

crystals in semicircular canals


• Inner ear

– Meniere's disease

• Amount of fluid in inner ear increases

intermittently, producing vertigo, fluctuating hearing

loss, and tinnitus

– Tinnitus

• Ringing, buzzing, or roaring sound in one or both

ears

• May be associated with prolonged exposure to

loud noises


• Hearing loss

– Acoustic neuroma

• Brain tumor adjacent to the cranial nerve

– Deafness

• Complete or partial loss of ability to hear

– Presbycusis

• Gradual loss of sensorineural hearing related to

aging

– (-cusis: hearing)


• Hearing loss

– Conductive hearing loss

• Sound waves are prevented from passing air to

fluid-filled inner ear

– Sensorineural hearing loss

• Due to damage to auditory nerve or hair cells in

inner ear

Diagnostic Procedures of Ears and Hearing

• Audiological evaluation

– Measurement of the ability to hear and

understand speech sounds based on pitch

and loudness

• Audiometry

– Use of audiometer to measure hearing acuity

• (audi/o: hearing)


• Otoscope

– Instrument used to examine external ear

canal

• Monaural testing

– Involves one ear

• (mon-: one; aur: hearing)

• Binaural testing

– Involves both ears

• (bin-: two)


• Tympanometry

– Use of air pressure in ear canal for testing the

disorders of middle ear

• Acoustic reflectometry

– Tests for sound reflection from eardrum

determining amount of fluid in middle ear

• Weber and Rinne tests

– Use of tuning fork to distinguish between

conductive and sensorineural hearing losses

Treatment Procedures of Ears and Hearing

• Outer ear

– Otoplasty

• Surgical repair, restoration, or alteration of pinna

• Middle ear

– Ear tubes (tympanostomy tubes)

• Ventilating tubes inserted into the eardrum to

provide drainage for fluid and relief of pressure


• Middle ear

– Mastoidectomy

• Surgical removal of mastoid cells

– Myringotomy

• Surgical incision in eardrum to relieve pressure

– Stapedectomy

• Surgical removal of the top portion of the stapes

and insertion of prosthetic device


• Middle ear

– Tympanoplasty

• Surgical correction of damaged middle ear

• Inner ear

– Labyrinthectomy

• Surgical removal of all or portion of labyrinth

– Vestibular rehabilitation therapy

• Physical therapy to treat variety of balance

disorders

Treatments for Hearing Loss

• Assistive listening device

– Transmits, processes, or amplifies sound

– Used with or without hearing aid

• Cochlear implant

– Bypasses damaged portion of ear and directly stimulates auditory nerve

• Fenestration

– New opening in the labyrinth to restore hearing

Treatments for Hearing Loss

• Hearing aids

– Electronic devices worn to correct hearing

loss

– Analog hearing aid

• Uses microphone to detect/amplify sounds

– Digital hearing aid

• Computer chip converts incoming sound into code

that is filtered before being amplified

Documents

Chapter 11 · PDF file · 2016-04-05audit/o, ot/o Outer ear pinn/i Middle ear myring/o, tympan/o Inner ear labyrinth/o. Functions of Eyes •Receptor organs of sight •Receive images