Chapter 20 - Eye Flashcards
Three layers of the eyeball
Outer - scleral
uveal
Retinal layer
where is the first refraction of light?
cornea
where is the second refraction of light?
lens
what structure can accommodate its shape to see far away or close up?
lens
what shape does the lens take during accommodation?
rounded
where are photoreceptors?
retina
rods
light
cones
acuity, color
what structure provides the greatest visual acuity?
macula (post on the retina)
what structure provides the best vision?
fovea
what fluid cleans the lens and retina?
aqueous humor
what glands produce tears?
lacrimal
what is strabismus?
crossed eyes
etiology of strabismus
eye muscles don’t work together and it confuses the brain. the brain then ignores image from the weaker eye causing ambylyopia (lazy eye)
what is nystagmus?
fast uncontrollable eye movements in one or both eyes
etiology of nystagmus
congenital or acquired from head injury, stroke, inner ear disorders, or drugs/medication (most common)
sneller eye chart
how much you can see from 20 ft away (20/20),
ophthalmoscope
tool used to examine the retina
tonometer
tool used to measure intra-ocular pressure
slit-lamp
tool used to examine the cornea, iris, and lens
hyperopia
farsighted, trouble seeing close up
myopia
nearsighted, trouble seeing far away (more common)
presbyopia
vision loss with age
astigmatism
curvature in cornea
symptoms of myopia
blurred vision, squinting when looking at far objects
symptoms of hyperopia
difficulty focusing on near objects
treatment for refractive disorders
LASIK - both disorders
lens implant - myopia (nearsightedness only)
treatment for myopia
concave lenses
treatment for hyperopia
convex lenses
treatment for astigmatism
glasses or hard contact lenses
presbyopia treatment
reading glasses or bifocal lenses
what is conjunctivitis
inflammation of the conjunctiva *pink eye
is pink eye contagious?
yes
what is the cause of conjunctivitis?
bacterial (most common), fungal, viral, or related to injury
corneal keratitis
infection of cornea, unilateral, leads to scarring –>vision loss
corneal keratopathy (band)
calcium deposits within cornea, creates a band – pain, decreased acuity
corneal dystrophy
clouding of cornea from abnormal accumulation
*bilateral
*genetic
is corneal dystrophy genetic?
yes
cataracts
cloudy lens
what is the leading cause of blindness in adults?
cataracts
is cataracts age associated?
yes - 90% of adults have some by 65
treatment for cataracts
LASIK surgery `
glaucoma
damaged optic nerve from increased intraocular pressureis
is glaucoma reversible or irreversible?
irreversible
why does IOP increase with glaucoma?
there’s a buildup of aqueous humor from the ciliary body
what is a common symptom of glaucoma?
light halos
is glaucoma an emergency?
yes - possible loss of vision within 1 day
risk factors for glaucoma
age
refractive disorders
genetics
other diseases (hypertension and diabetes)
retinal detachment
retina peels away from support tissue
is retinal detachment an emergency?
yes - can lead to blindness
symptoms of retinal detachment
spots, floaters, and flashes of light – NOT painful
Etiology of retinal detachment
trauma to eye
Marfan syndrome
extreme nearsightedness
How do reattach the retina? - treatment
surgery to reattach
macular degeneration
damage to macula - does not lead to complete loss of vision
what is the leading cause of vision loss in people over 60?
macular degeneration
risk factors for macular degeneratation
age
obesity
UV light exposure
smoking
family history
ethnicity
what is the treatment for macular degeneration?
no cure
symptom of macular degeneration
blurry dark spot in the middle of visual field
hypertensive retinopathy
damage to retina due to hypertension
hypertensive retinopathy symptoms
dim vision
vision loss
double vision
is hypertensive retinopathy reversible?
yes - with treatment
diabetic retinopathy
damage to blood vessels in retina from diabetes
what can diabetic retinopathy lead to?
microhemorrhages
edema
neovascularization (new blood vessels)
symptoms of diabetic retinopathy
spots/floaters in eyes
blurred vision
empty spot in vision
treatment for diabetic retinopathy
blood glucose control
surgery to seal leaky vessels
how many more times are diabetics to go blind than normal people?
20x more likely
other diseases in diabetics
glaucoma
retinal detachment
cataracts
diabetic retinopathy
color blindness
deficiency of certain cones
red-green color vision defects
deficiency in red/green cones
blue-yellow color vision defects
trouble differentiating shades of blue and green
what type of genetic disease is color blindness?
X-linked
Autosomal recessive
retinoblastoma
cancer of the eye in children
what type of genetic disease is retinoblastoma?
autosomal dominant - Rb1 gene
malignant melanoma
cancer of the eye in adults – arise from melanocytes in the choroid layer and iris
malignant melanoma has a worse prognosis than ……. melanoma
skin
what is the definition of blindness
visual acuity of 20/200
causes of blindness
lesions
developmental causes
trauma
