Download refraction disorder

SPECIAL SENSES
Lori Mathis, CST
ST 110
OBJECTIVES
Describe the functions and structures
of the eyes and adnexa
Recognize, define, spell, and pronounce
terms related to the pathology, diagnostic
and treatment procedures of eye disorders
OBJECTIVES CONT.
Describe the functions and structures
of the ears
Recognize, define, spell, and pronounce
terms related to the pathology, diagnostic
and treatment procedures of ear disorders
FUNCTIONS OF THE EYE
The eye is a sensory and receptor
organ that receives images and
transmits them to the brain
EYE TERMINOLOGY
Optic: pertaining to the eye or sight
Ocular: pertaining to the eye
Extraocular: outside the eyeball
Intraocular: within the eyeball
STRUCTURES OF THE EYE
Adnexa: (also known as adnexa oculi)
includes orbit, eye muscles, eyelids,
eyelashes, conjunctiva, and lacrimal apparatus
Orbit: (also know as the eye socket) bony
cavity of the skull that contains and protects
the eyeball and its associated muscles, blood
vessels, and nerves
EYE MUSCLES
Six major muscles attached to each eye
Provide for wide range movement
Work together in coordinated movements
that enable normal binocular vision
NOTE: Binocular refers to the use of
both eyes working together
THE EYELIDS
Upper & Lower lids protect the eyeball from
- Foreign matter
- Excessive light
- Impact
Canthus: angle where upper and lower
eyelids meet
Inner canthus: where the eyelids meet
nearest the nose
EYELIDS CONT.
Epicanthus: vertical fold of skin on either
side of the nose
Tarsus: (also known as the tarsal plate)
plate like framework within the
upper and lower eyelids that
provides stiffness and shape
THE EYEBROWS & EYELASHES
Prevent foreign matter from reaching the eyes
Edges of the eyelids contain cilia (eyelashes)
and oil-producing sebaceous glands
THE CONJUNCTIVA
Mucous membrane that lines the underside of
each eyelid and continues to form a protective
covering over the exposed surface of the eyeball
and oil-producing sebaceous glands
THE LACRIMAL APPARATUS
(Also known as tear apparatus) consists of
structures that produce, store, and remove tears
Lacrimal glands: located above the outer corner
of each eye. Secrete lacrimal
fluid (tears)
Lacrimation: normal continuous tear secretion
Lacrimal canaliculi: ducts in the inner corner of
each eye. Collect tears and
drain into lacrimal sac
THE LACRIMAL APPARATUS CONT.
Lacrimal sac: known as dacryocyst or tear sac.
The enlargement of the upper part
of the lacrimal duct
Lacrimal duct: known as the nasolacrimal duct,
Is the passageway that drains
lacrimal fluid into the nose
THE EYEBALL
Also known as the globe. It is a
1-inch sphere with walls made up
Of three layers:
- Sclera
- Choroid
- Retina
It is also divided into anterior and
Posterior segments
THE SCLERA
The “white of the eye”
Outer fibrous tissue layer of the eye
Maintains the shape of the eye and protects the
delicate inner layers of tissue
Cornea: is the transparent anterior portion of the
sclera
NOTE: The cornea provides most of
the optical power of the eye
THE UVEAL TRACT
Known as the uvea and is the vascular layer of
the eye. Includes the:
- Choroid
- Iris
- Ciliary body
THE CHOROID
Choroid layer or choroid coat
The opaque middle layer of the eyeball
Contains many blood vessels and provides the
blood supply for the entire eye
The Iris
Pigmented
(colored)
muscular layer
that surrounds
the pupil
THE PUPIL
The black circular
opening in the
center of the
iris that permits
light to enter the
eye
HOW THE PUPIL WORKS
Muscles within the iris control the amount of
light that is allowed to enter
To decrease the amount of light these circular
muscles contract and make the opening smaller
To increase the amount of light, the muscles
dilate (relax) and make the opening larger
THE LENS
(Also known as the crystalline lens, is a clear,
flexible, and curved structure that focuses
mages on the retina.
It is held in place by the suspensory ligament
from the ciliary body.
THE CILIARY BODY
Located within the choroid
Set of muscles and suspensory ligaments that
adjust the lens to refine the focus of light rays
on the retina
To focus on nearby objects, these muscles
adjust to make the lens thicker
To focus on distant objects, these muscles
stretch the lens so it is thinner
THE RETINA
Sensitive inner nerve layer of the eye located
between the posterior chamber and the choroid
layer at the back of the eye
Contains specialized light-sensitive cells called
rods ( black and white receptors) and cones
(color receptors)
Rods and cones receive images and convert
them into nerve impulses
THE MACULA LUTEA
Clearly defined yellow area in the center of the
retina
This is the area of sharpest central vision
THE FOVEA CENTRALIS
The pit in the middle of the macula lutea.
Color vision is best because of high
concentration of cones
THE OPTIC DISC
The BLIND SPOT (NO Rods or Cones)
Nerve endings of the retina gather to form the
optic nerve
THE OPTIC NERVE
Cranial nerve II (two)
Transmits nerve impulses from the retina
to the brain
ANTERIOR EYE SEGMENT
• Front 1/3 of the eye is divided into anterior
and posterior chambers
-- Anterior chamber: behind the inner
surface of the cornea and in front of
the iris
-- Posterior chamber: located between
the back of the iris and the front of the
lens
ANTERIOR SEGMENT CONT.
• Filled with aqueous humor
• Fluid nourishes the intraocular structures
• through the trabecular meshwork and the
• canal of Schlemm
• Constant drainage regulates intraocular
• pressure
NOTE: Humor is any clear body liquid
or semifluid substance
POSTERIOR EYE SEGMENT
• Posterior 2/3 of the eyeball is filled with vitreous
humor
• This jelly-like mass aids the eye in maintaining
its shape
• Lined with retina and its related structures
NORMAL ACTIONS OF THE EYE
Accommodation: process by which the eye
makes adjustments for seeing objects at
varying distances
Convergence: simultaneous inward movement
of both eyes (toward each other) usually an
effort single binocular vision
Emmetropia: normal relationship between the
refractive power of the eye and the shape of
eye that enables light rays to focus correctly
on the retina.
Refraction: ability of the lens to bend the
light rays to help them focus on the retina
Normal eye: Light rays focus
on the retina
REFRACTIVE DISORDERS
Hyperopia: (farsightedness) Light rays
focus beyond the retina
REFRACTIVE DISORDERS
Myopia: (nearsightedness) Light rays
focus in front of the retina
VISUAL ACUITY
Ability to distinguish object details and shape
at a distance. Normal vision stated as 20/20
Snellen Chart: used to measure visual acuity
First number indicates the distance from the
chart which is a standard 20 feet
Second number indicates the deviation from
the norm based on the ability to read lines of
letter on the chart
EYELID PATHOLOGY
Blepharoptosis: drooping of the upper eyelid
Ectropion: eversion (turning outward) of the
edge of the eyelid
Entropion: inversion (turning inward) on the
edge of the eyelid
Hordeolum: (stye) an infection of one or more
glands at the border of the eyelid
Chalazion: localized swelling of the eyelid
resulting from sebaceous gland obstruction
ADNEXA PATHOLOGY
Dacryocystitis: inflammation of the lacrimal
sac and is associated with faulty tear drainage
Conjunctiva: (pinkeye) inflammation of the
conjunctiva
Xerophthalmia: (dry eye) drying of eye
surfaces characterized by the loss of luster
of the cornea and conjunctiva
SCLERA, CORNEA, IRIS
Scleritis: inflammation of the sclera
Snellen Chart: used to measure visual acuity
Keratitis: inflammation of the cornea
Corneal Abrasion: injury such as a scratch or
irritation to the outer layers of the cornea
Corneal Ulcer: pitting of the cornea caused by
infection or injury
Iritis: inflammation of the iris
EYE
Anisocoria: condition in which the pupils are
unequal in size
Cataract: loss of transparency of the lens. May
be congenital or caused by trauma or disease
Papilledema: swelling and inflammation of the
optic nerve at the point of entrance through the
optic disc
Floaters: (vitreous floaters) particles that float in
the vitreous fluid and cast shadows on the retina
EYE
Nystagmus: involuntary, constant rhythmic
movement of the eyeball
Retinal Detachment: retina is pulled away from it
normal position of being attached to the choroid
Uveitis: inflammation anywhere in the uveal trac
May affect the choroid, iris, or ciliary body
GLAUCOMA
Characterized by increased intraocular pressure
GLAUCOMA
Open-angle Glaucoma: most common form.
Trabecular meshwork becomes detached.
Closed-angle Glaucoma: the opening between
the cornea and iris narrows so that fluid can’t
reach the trabecular meshwork
NOTE: glaucoma does not produce symptoms
noticed by the patient until the optic nerve
has been damaged. Regular eye exams
can detect this before damage occurs
MACULAR DEGENERATION
Gradually progressive condition that results in th
loss of central vision but not in total blindness
MACULAR DEGENERATION CONT.
Dry-type Degeneration: accounts for 90% of
cases. Caused by the atrophy of the macula
Wet-type Degeneration: associated with
formation of new blood vessels that produce
hemorrhages
FUNCTIONAL DEFECTS
Diplopia: (double vision)
Hemianopia: blindness in one half of visual field
Monochromatism: color blindness
Nyctalopia: night blindness
Presbyopia: changes in eyes that occur with
aging
STRABISMUS
Known as a squint
Disorder in which eyes cannot be directed in a
parallel manner toward the same object
Estropia: also known as cross-eyes. Inward
deviation of one eye in relation to the other
Extropia: also known as wall-eye. Outward
deviation of one eye relative to the other
REFRACTIVE DISORDERS
A condition in which the lens and cornea do not
bend light to that it focuses properly on the retina
NORMAL VISION
REFRACTION DISORDER
HYPEROPIA (FARSIGHTEDNESS)
REFRACTION DISORDER
MYOPIA (NEARSIGHTEDNESS)
DISORDERS
Ametropia: error of refraction in which only
objects located a finite distance from the eye
are focused on the retina
Astigmatism: eye does not focus properly
because of unequal curvatures of the cornea
Hyperopia: defect in which light rays focus
beyond the retina (farsightedness)
Myopia: defect in which light rays focus in
front of the retina (nearsightedness)
BLINDNESS
Amblyopia: dimness of vision or partial loss
of sight without detectable disease of the eye
Blindness: inability to see. Legally blind
is when best-corrected vision is 20/200
Scotoma: abnormal area of absent or
depressed vision surrounded by an area
of normal vision (blind spot)
DIAGNOSTIC PROCEDURES
Visual Acuity Measurement: evaluation of the
eye’s ability to distinguish object details and
shapes
Refraction: determine eye’s refractive error and
best corrective lenses to be prescribed
Tonometry: measures intraocular pressure
Dilate: administering paralyzing mydriatic drops
that forces the pupil to remain wide open even in
the presence of light
SPECIALIZED DIAGNOSTIC PROCEDURES
Flourescein Staining: used to visualize
corneal abrasions
IV Flourescein Angiography: (IFA) dye
injected into arm and pictures taken as the
dye passes through blood vessels in the
retina. Detects leaking blood vessels within
the eye
Visual Field Test: determines losses in
peripheral vision
TREATMENT PROCEDURES
Orbitotomy: surgical incision into the orbit
for biopsy, abscess drainage, tumor removal
or foreign body removal
Tarsectomy: surgical removal of a segment
of the tarsal plate of the upper or lower eyelid
Tarsorrhaphy: partially or completely
suturing together the upper and lower eyelids
Conjunctivoplasty: surgical repair of the
conjunctiva
Keratoplasty: corneal transplant. Replacement
of
scarred or diseased cornea
Iridectomy: surgical removal of part of the iris
Radial Keratotomy: used to correct myopia.
Partial incisions are made in the cornea causing
it to flatten
Lensectomy: surgical removal of a cataract
clouded lens
Intracapsular Cataract Extraction: removal of
a cloudy lens including the surrounding capsule
Phacoemulsificaton: use of ultrasonic vibration
to shatter and break up a cataract; easier removal
Intraocular Lens: plastic lens surgically implanted
to replace the natural lens
Aphakia: absence of the lens of an eye after
cataract extraction
Pseudophakia: natural lens is replaced with an
intraocular lens
LASER TREATMENTS
Laser Trabeculoplasty: creates an opening that
allows fluid to drain properly to prevent pressure
buildup in the eye
Laser Iridotomy: creates an opening in the iris to
allow proper drainage
Retinopexy: reattachment of a detached retina
Sealing leaking or damaged blood vessels
Photorefractive Keratectomy: reshaping top layer
of the cornea. (PRK)
STRUCTURES OF THE EAR
Divided into three separate regions:
-- Outer ear
-- Middle ear
-- Inner ear
OUTER EAR
Pinna/Auricle: external portion of the ear
Catches sound waves and transmits them to
the external auditory canal
External Auditory Canal: transmits sound waves
from the pinna to the middle ear
Cerumen/Earwax: protective functions
MIDDLE EAR
Tympanic Membrane/Eardrum: located between
the outer and external portions of the ear
When sound waves reach it, the TM transmits
the sound by vibrating
Mastoid Sinus: hollow air spaces located in
the mastoid process.
An infection in the middle ear can spread
rapidly to these cells
AUDITORY OSSICLES
Three small bones found in the middle ear
Transmits sound waves from the eardrum to
the inner ear by vibration
Malleus: known as the “hammer”
Incus: known as the “anvil”
Stapes: known as the “stirrup”
EUSTACHIAN TUBES
Narrow tubes which lead from the middle
ear to the nasopharynx
Equalize air pressure in the middle ear with the
outside atmosphere
Oval Window: located under the base of the
stapes; separates the middle ear from the
inner ear
INNER EAR
Contains the sensory receptors for hearing
and balance
Cochlea: spiral-shaped passage leading from
the oval window
Cochlear Duct: located within the cochlea.
Filled with fluid and vibrates when sound
waves strike it
INNER EAR CONT.
Organ of Corti: located within the cochlea. Is
the receptor site that receives these vibrations
and relays them to the auditory nerve fibers that
transmit them to the auditory center of the
cerebral cortex, where they are interpreted and
heard
Semicircular Canals: located within the inner
ear and contain endolymph and hairlike cells.
Helps maintain equilibrium
INNER EAR CONT.
Acoustic Nerves: cranial nerve VII, transmits
this information to the brain and the brain sends
a message to muscles in all parts of the body
to insure that equilibrium is maintained
NORMAL EAR ACTIONS
Air Conduction: Sound waves enter the ear
through the pinna, travel down the auditory
canal, and strike the TM between the outer
and middle ear.
Bone Conduction: Eardrum vibrates, it moves
the auditory ossicles and these conduct sound
waves through the middle ear
Sensorineural Conduction: vibrations reach the
inner ear via the oval window. The structures in
the inner ear receive the sound and relay them to
the brain
OUTER EAR PATHOLOGY
Impacted Cerumen: accumulation of cerumen
that forms a solid mass adhering to the walls of
the external auditory canal
Otalgia: known as an earache
Otitis: any inflammation of the ear
Otopyorrhea: flow of pus from the ear
Otorrhagia: bleeding from the ear
MIDDLE EAR PATHOLOGY
Eustachitis: inflammation of the eustachian tube
Mastoiditis: inflammation of any part of the
process
Myringitis: inflammation of the TM
Otosclerosis: ankylosis of the bones of the
middle ear resulting in a conductive hearing loss
OTITIS MEDIA PATHOLOGY
Acute Otitis Media: inflammation of middle ear
usually associated with upper respiratory tract
infection. Most commonly in children
Serous Otitis Media: fluid buildup in the middle
ear that may follow acute otitis media
Otitis Media with Effusion: escape of fluid from
blood or lymphatic vessels into the tissues or a
cavity
Purulent Otitis Media: buildup of puss in the
middle ear
INNER EAR PATHOLOGY
Labryinthitis: inflammation of the labyrinth
resulting in vertigo
Meniere’s Syndrome: chronic disease of the
inner ear characterized by three main symptoms:
-- Vertigo, fluctuating hearing loss, tinnitus
Tinnitus: ringing, buzzing, or roaring in the ears
HEARING LOSS
Deafness: complete or partial loss of the ability
to hear
Conductive Hearing Loss: outer or middle ear
does not conduct sound vibrations to the inner
ear normally
Noise-Induced Loss: result of loss of sensitive
hairlike cells of the inner ear
Sensorineural Loss: nerve deafness
Presbycusis: progressive age related hearing loss
TREATMENT PROCEDURES
Otoplasty: surgical repair of the pinna
Mastoidectomy: surgical removal of mastoid cells
Myringectomy: surgical incision of the eardrum
Tympanoplasty: surgical correction of a damaged
Stapedectomy: surgical removal of the stapes
Labyrinthectomy: surgical removal of the labyrinth