S14 Diseases of the Eyes & Ears

1. sclera

2. uvea

3. retina

three layers of the eyeball

sclera

fibrous connective tissue that lends shape and support to the eye; visible white of eye

uvea

vascular layer of the eye that provides oxygen and nutrients to the retina

retina

inner and posterior layer of the eye that contains photoreceptors

photoreceptors

light-sensitive nerve endings in the retina

macula

the center of the retina with a high density of photoreceptors; responsible for acute vision

vitreous humor

thick fluid that fills the eyeball posterior to the lens; maintains eyeball shape

aqueous humor

fluid that fills the space in front of the lens

cornea

curved, transparent structure in front of the lens that covers the anterior surface of eyeball; this is where light first enters eye

lens

transparent biconcave structure composed of protein

focuses light onto the retina

function of lens

iris

flattened disc with a central opening

pupil

central opening in the iris that allows lights to enter to the lens

dilated pupil

a widen pupil that permits more light to enter; occurs when there is low light

constricted pupil

narrow pupil that permits little light to enter; occurs when there is a lot of light

eyelids

skin-covered flpas that close and protect eye surface

tear glands

secrete lubricating fluid onto outer surface of the eye

ophthalmoscope

dx procedure that reveals the condition of retina, macula, and cornea

tonometry

measures eyeball pressure to detect glaucoma

Snellen eye chart

used to assess visual acuity

refractive errors

type of diseases that produce improperly focused light in the retina, which results in blurry images; most common vision problem in U.S.

myopia

nearsightedness, where eye focuses on near objects, but not far objects

hyperopia

farsightedness, where eye focuses on distant objects but can’t focus on near objects

family history because it is inherited

most important risk factor for myopia and hyperopia

eyeball grows too long; distant images focus before or short of retina

what is eyeball shape for myopia

eyeball is too short and distant images focused behind retina, but close images are unfocused on retina

what is eyeball shape for hyperopia

concave lens

what type of lenses are used for myopia

convex lens

what type of lenses are used for hyperopia

it shapes the cornea

how can laser surgey correct myopia and hyperopia

presbyopia

age-related refractive disorder where eye can’t focus on close objects

some have small amount starting at 35 but it is most noticeable in late 40s

when does presbyopia start

dilated eye exam and Snellen eye chart

dx for presbyopia

astigmatism

cornea with surface irregularities that cause light to be unfocused on retina and produce images with blurry regions

Diabetic retinopathy

leading cause of blindness among adults in U.S

diabetes mellitus (damages blood vessels)

chief risk factor for diabetic retinopathy

annual eye exams and tx for diabetes and hypertension

prevention for diabetic retinopathy

retina vascular changes

loss of visual acuity

diminished night vision

symptoms of diabetic retinopathy

laser surgery stems vessel hemorrhage

treatment for diabetic retinopathy (DR)

macular degenetation

disease that results in reduction or loss of acute vision; leading cause of vision loss in adults

affects the macular where sharp images are formed. results in affected central vision but normal peripheral vision

what does macular degeneration affect

1. atrophic (dry) form

2. exudative (wet, hemorrhagic) type

two forms of macular degeneration

atrophic (dry) form

type of macular degeneration where the macular ara degenerates; more than 90% of cases

exudative (wet) type

type of macular degeneration where capillaries under the macula leak and disrupt the macula

obstruction of blood flow, revascularization, and damaged retina

how does macular degeneration cause acute vision

age (usually over 50)

family history

smoking

risk factors for macular degernation

1. inability to see faces clearly

2. difficulty reading

3. problems performing close work (ie. sewing)

s/s for macular degeneration

Amsler grid

made of grid of fine lines that can detect distorted, incomplete, or wavy images in central vision field

Fluorescein angiography

uses dye injected intravenously and a special camera to reveal leaking vessels below the retina

there is no cure

1. some reduction of wet form with laser therapy

2. vitamin supplementation

3. surgical implantation of telescopic lens can improve central vision

tx for macular degeneration

retinal detachment

emergency condition where retina pulls away from back of eyeball; can result in blindness

1. age

2. extreme myopia

3. advanced diabetes

4. eye trauma

risk factors for retinal detachment

1. sudden appearance of floaters (floating debris) in affected eye

2. sudden flashes of light or dark shadows

symptoms of retinal detachment

laser surgery of injection of gas or fluid to press retina back into place

treatment for retinal detachment

glaucoma

increased intraocular pressure in eye that damages optic nerve; leading cause of blindness in U.S.

people over age 60, mostly Mexican American

people over age 40, mostly African American

who has highest risk for glaucoma

not completely known but related to fluid pressure buildup

what is the cause of glaucoma

pachymetry

measures the thickness of the cornea

tonometry, visual field testing, and pachymetry

what tests are done for glaucoma

those with corneal thickness can have high-pressure readings on tonometry even when there is no glaucoma; this test is done to prevent misdiagnosis

why is a pachymetry done when testing for glaucoma

aimed at decreasing intraocular pressure

1. laser surgery

2. medications (eye drops that reduce production of fluid and promote fluid drainage)

tx for glaucoma

cataract

clouding of the lens mostly related to aging

age-associated happens in both lenes' of he eyes, but congenital can happen in one eye

difference between age-associated, and congenital cataracts

1. visual distortion

2. blurred vision

3. glare, especially in birth light or night

visual impairments of cataracts

conjunctivitis

inflammation of the conjunctiva; aka pink eye

conjunctiva

superficial covering of the sclera and the inner lining of the eyelids

bacteria, viruses, or irritating chemicals

causes of conjunctivitis

itchy, light-sensitive, red eyes with yellow or white discharge

symptom of bacterial conjunctivitis

inclusion conjunctivitis

type of conjunctivitis that is sometimes present in newborns; caused by Chlamydia trachomatis and is transmitted during childbirth in mothers with chlamydia

bacterial - antibiotics

viral - no cure

tx for conjunctivitis

keratitis

inflammation of the cornea

bacteria, virus, fungi, parasites

what organisms cause keratitis

uveitis

inflammation of the uvea

1. pain

2. redness

3. photophobia

4. blurred vision

symptoms of uveitis

corticosteroids and systemic or topical medications

treatment for uveitis

immune deficiency

risk factor for uveitis

1. cytomegalovirus

2. herpes simplex

3. Toxoplasma

4. Candida

what can cause uveitis in those with HIV/AIDs

stye or hordeolum

most noticeable lesions found on the eyelid

infection with Staph bacteria, which causes abscess formation

etiology for hordeolum

project toward surface of eye

where do internal styles project toward

wash with washcloth or antibiotic eye drops

tx for styes

cones

photoreceptors that detect color

cannot distinguish shades of red and green

most people with impaired color vision cannot distinguish what

color blindness

complete absence of color vision and can only see shades of grey; rare

genetic trait carried on X chromosome; makes males more susceptible

etiology of color impairments or blindness

retinoblastoma

rare, recessively inherited childhood tumor of the retina

1. crossed eyes

2. eye pain

3. redness

4. appearance of leukocoria

symptoms of retinoblastoma

leukocoria

white reflex in the pupil that are distinctive sign of retinoblastoma; aka cat’s eye reflex

pinna

portion of the outer ear that is external to the skull; directs sound into auditory canal

auditory canal

tube that leads from pinna to middle ear; innermost part is lined with glands that secret cerumen

cerumen

waxy substance that keeps typanic membrane soft and flexible

1. malleus

2. incus

3. stapes

the three auditory ossicles

stapes

the auditory ossicle that vibrates against the cochlea opening

cochlea

snail-shaped organ in inner earth that stimulates hair cells to transmit info to auditory nerve

vestibular apparatus and semicircular canals

structures int he inner ear that give brain info about balance maintainence

cerumen impaction

excess wax buildup in ear

tinnitus, earache, diminished hearing

s/s of cerumen impaction

do not clean ear with cotton swab since this pushes the wax further down the ear; instead apply baby oil or hydrogen peroxide to soften cerumen

prevention for cerumen impaction