chap 20 - disorders of the eye (start of final unit)

Question 1

three layers of the eye

Answer 1

1) outer sclera
2) uveal layer
- iris, ciliary body and choroid
3) retinal layer

Question 2

conjunctiva

Answer 2

tissue on the inner surface of the eyelids

Question 3

cornea

Answer 3

light enters, first refraction

Question 4

lens

Answer 4

second site of refraction, accomodation

Question 5

accomodation

Answer 5

by changing shape the lens can focus light rays
- Either flatten out the lens or round out the lens, important for when you are looking at something in the distance versus something close up

Question 6

pupil

Answer 6

controlled by your iris which is made of smooth muscle
- controls how much light is allowed into the eye

Question 7

retina

Answer 7

photoreceptors

Question 8

macula

Answer 8

post on the retina that provides the greatest visual acuity, most cones are located here

Question 9

fovea

Answer 9

central portion of the macula

Question 10

aqueous humor

Answer 10

watery fluid that nourishes and cleanses the avascular lens and retina
- continually recirculating

Question 11

lacrimal gland

Answer 11

keeps eyes moist, flush foreign debris away, produce mucus that allows eyelid to slide smoothly over eye

Question 12

lens and accomodation

Answer 12

lens changes shape by ciliary muscle

Question 13

most frequent and serious problems

Answer 13

• decrease in visual acuity
• Age-related macular degeneration
• Trauma
• Acute conjunctivitis
• Cataract
• Glaucoma

Question 14

symptoms and signs

Answer 14

Decreased visual acuity resulting from:
Visual field defects
Focal areas of blindness
Pain
Manifestation of trauma, infection or increased intraocular pressure
Blurred vision
Accompanies various systemic diseases
Strabismus
amblyopia
nystagmus

Question 15

strabismus

Answer 15

“Crossed eyes”
Etiology
- Eye muscles don’t work together - 6 different muscles on each eye
- Confuses the brain
- Brain ignores image from weaker eye
Amblyopia “lazy eye”

Question 16

nystagmus

Answer 16

Fast, uncontrollable eye movements
One eye or both eyes
Etiology
- Congenital
- Acquired
- Head injury
- Stroke
- Inner ear disorders
- drugs/medication

Question 17

tests

Answer 17

Visual acuity tests
Ophthalmoscope
- Used to examine the retina
Tonometer
- Measures intraocular pressure
Slit-lamp
- Used to examine the cornea, iris, and lens

Question 18

refraction disorders

Answer 18

hyperopia, myopia, presbyopia, astigmatism

Question 19

hyperopia

Answer 19

(farsighted)
Can see far things
Trouble seeing close things
Eyeball is too short

Question 20

myopia

Answer 20

(nearsighted)
Trouble seeing far things
Eyeball is too long

Question 21

presbyopia

Answer 21

Accommodation changes
Age

Question 22

general symptoms of refraction disorders

Answer 22

General
Poor vision
Headaches
Eyestrain
Fatigue
Burning

Question 23

symptoms of myopia

Answer 23

Blurred vision
Squinting when looking at distance objects

Question 24

hyperopia symptoms

Answer 24

• difficulty focusing on near objects

Question 25

treatment

Answer 25

Procedures
- Laser-assisted in situ keratomileusis (lasik)
- Both types of disorders
- Phakic intraocular lens implant
- Nearsightedness
- Myopia
- Concave lens
- Hyperopia
- Convex, lens
- Astigmatism
- Glasses or hard contact lenses
- Presbyopia
- Reading glasses or bifocal lenses

Question 26

conjuctivitis

Answer 26

Inflammation = can be bacterial, fungal, viral or related to allergy
- Most commonly associated with bacteria and most often found in children
- Contagious
- Treated with antibiotics
Also known as: pink eye

Question 27

corneal keratitis

Answer 27

Infection (bacteria, viral, fungus, protozoa)
Typically unilateral
Can lead to vision loss from scarring
Keratin gets into the cells of the cornea = could be from infection

Question 28

corneal keratopathy

Answer 28

(band keratopathy)
Deposition of calcium salts within cornea
Leads to pain, decreased acuity

Question 29

corneal dystrophy

Answer 29

Bilateral
Genetic - which is why it affects both eyes
Abnormal accumulation in cornea
Clouding of cornea
Could be treated with a cornea transplant - doesn’t have to be a specific match because the immune system doesn’t go into the anterior chamber of the eye

Question 30

cataracts

Answer 30

= opacity of lens
- Age related degeneration - constant UV light coming into the eye over long periods of time
- Leading cause of blindness in adults worldwide
- Age associated
- By 65, 90% adults will have some
Symptoms
- Pupil looks milky white
Treatment
- Surgery = swap out the old lens for a new lens

Question 31

glaucoma

Answer 31

Optic nerve is damaged by abnormally increased intraocular pressure (IOP)
- Irreversible
Second most common cause of blindness in world
Build up of aqueous humor
- Intraocular pressure
Signs and symptoms
- Acute glaucoma: possible loss of vision within 1 day = emergency
- Severe eye pain
- Blurred vision
- Eye redness
- Light halos
- Nausea
- Vomiting
- Risk factors
- Age
- Refractive disorders
- Genetics
Other diseases
- Hypertension
-Diabetes

Question 32

retinal detachment

Answer 32

Retinal peels away from underlying support tissue
Medical emergency
- Can lead to blindness
Symptoms
- Spots, floaters, flashes of light
- Not painful
Surgical treatment to reattach
Etiology
- Trauma to eye
- Genetic disease - Marfan syndrome - disease of connective tissue, the CT is too weak to hold on to the retina
- Extreme nearsightedness

Question 33

macular degeneration

Answer 33

Leading cause of vision loss in people over 60
Damage to macular - only one part but one of the most important parts
- Does not lead to complete loss of vision
Risk factors
- Age-associated
- Obesity
- UV light exposure - why its important to wear sunglasses
- Smoking
- Family history
- Ethnicity
Treatment
- No cure - try to prevent it from happening

Question 34

hypertensive retinopathy

Answer 34

Etiology
- Damage to retina due to hypertension - high blood pressure causes pathology of the retina
- Vessel narrowing
- Microinfarcts = small areas of tissue death
- Hemorrhages
- exudates/edema = fluid leakage
Leads to:
- Dim vision
- Vision loss
- Double vision
Can be reversible with treatment - bring blood pressure down

Question 35

diabetic retinopathy

Answer 35

Retina sensitive to hyperglycemia
- Diabetes 20x to go blind than non-diabetics
- Damage to blood vessels in cornea
Can lead to:
- Microhemorrhages = small bleeding
- Edema
- Neovascularization = new blood vessels, we don’t want a lot of blood vessels in the eye because they can interrupt light waves coming in
Symptoms
- spots/floaters in eyes
- Blurred vision
- Empty spot in vision
Treatment
- Blood glucose control
- Surgery
- Seal leaking vessels

Question 36

eye diseases in diabetics

Answer 36

glaucoma, retinal detachment, diabetic retinopathy

Question 37

color deficient (blindess)

Answer 37

Color vision determined by cones
- Three types (red, blue, and green cones)
- Depends on relative output of these three types of cones
X-linked recessive = more common in men, most receive from their mothers
Types
- Red-green color vision defects - most common
- Defects in…
- Either red cone output or green cone output - one or the other
- Blue-yellow color vision defects
- Trouble differentiating shades if blue and green
- Complete absence of color vision
- No working cones = only black and white

Question 38

retinoblastoma

Answer 38

Children
Rare malignant tumor of retinal cells - usually the cones
Autosomal dominant inheritance
- Rb1 gene
Treatment = remove the eye = want to treat it early so it does not metastasize to the brain (which is super close by)

Question 39

malignant melanoma

Answer 39

Adults
Ocular melanoma
Arise from melanocytes - just like in the skin
- Choroid layer
- Iris
Worse prognosis than skin melanoma - because it metastasizes early

Question 40

organ failure - blindness

Answer 40

Defined as visual acuity 20/200
4/1000 people legally blind
Causes
- Lesions
- Developmental
- Trauma