chapter 15- vision Flashcards
what is apart of the visual system
eyes
accessory structures
optic nerve
tract
pathways
3 roles for the visual sytem
sight
eye movement
provide info for pastural and limb control
stimulus may be billions of miles away and still be detected
visual stimuli
info regarding light vs dark, movement and color
visual input
pathway for how eyes respond to light
initiate afferent AP-> optic nerves-> optic chiasma-> optic tracts to brain
how many pathways does the visual association area have and what are they
2
ventral & dorsal path
ventral path is where in the brain
temporal visual cortex
dorsal path is where in the brain
parietal virtual cortex
ventral path asks what question
what
dorsal path asks what questions
where
what does the frontal eye field do
interpret location of objects
7 bones surround eyeball and adipose tissues as well (posterior)
eye orbit bones
hair superior to eye orbit. prevent perspiration from running into eyes and irritating, it also shades from direct sunlight
eyebrows
palpebrae; works with eyelashes to protect from foreign objects, lubricates eye, regulates light entering eye, rapid blinking (25x/minute)
eyelids
what muscle opens eye
levator palpebrae
what muscle closes eyelid
orbicularis oculi
space between 2 open eyelids
palpebrae fissue
angle- join medial/lateral margin= blank= modified sebaceous/ sweat glands
canthus
5 layers
skin, areolar CT, skeletal muscles, tarsal plate (dense CT), and papebral conjunctiva
what forms shape of eyelid
tarsal plate
what lines inner eyelid
palpebral conjunctiva
2-3 layers of hair at free edge of eyelid
brush away dust/ foreign objects from eye
eyelashes
sweat glands that lubricates eyelash follicles
ciliary glands
gland inflammation at base of eyelash, usually bacterial infection, pain
stye
tarsal=sebaceous glands at inner margins of eyelids
sebum lubricates tears and restrains tears from flowing over eyelid margi. airtight
meibomian glands
meibomian cyst is
chalazion
chalazion=meibomian=
infection/ blockage of oil gland
is there pain in chalazion
lack pain
treatment for chalazion
warm compresses for 10-15 min/ 3-4 time a day
massage
antibiotics
I&D
steroid injection
opthalmologist
thin, transparent mucous membrane on eyelid, surface of eye, lubricate eye
conjunctiva
cover inner eyelid
palpebral conjunctiva
covers anterior white surface of the eye
bulbar conjuctiva
inflammation of conjuctiva
conjuctivitis
inflammation of conjuctiva=
pinkeye
is pinkeye contagious
yes
causes for conjunctivitis
bacterial
viral
allergic
foreign body or chemical splash
S&S for conjunctivitis
redness, itchy, gritty, discharge with crust, tearing, photophobia
treatment for conjunctivitis
contacts out
compresses
antiinflammatory drops
decongestants
steroids
antivirals
antibiotic eye frops
pataday
artifiical tears
what is innervated by parasympathetic fibers of facial CN VII
lacrimal gland
role in eye protection
lacrimal apparatus
producing tears ->
lacrimal ducts and across anterior eye surface
lacrimal gland goes into
lacrimal sac and through nasolacrimal duct into nasal cavity
what moisturize eye surface, lubricate eyelids, wash away foreign body
lacrimal gland
what is tear composition
predominately H2O, salt, mucus, lysozyme, immunoglobulins
6 extrinsic eye muscles
superior, inferior, medial, lateral rectus
superior, inferior oblique
4 extrinsic eye muscles are controlled by? and what are they
oculomotor CNIII, SR,IR, MR, IO
1 extrinsic eye muscle are controlled by
abducens and trochlear
abducens controls what muscle
LR
trochlear controls what muscle
SO
hollow sphere filled with vitreous humor
eyeball
3 tunics comprise wall:
fibrous tunic
vascular tunic
nervous tunic
outer. sclera and cornea
fibrous
middle. choroid, cillary body and iris
vascular
inner. retina
nervous
white of the eye, posterior 5/6. firm, opaque tissue= dense CT with elasticity
maintains shape of eye, protects internal area, attachment for muscles
sclera
anterior, avascular, transparent structure, stratified squamous epithelium
inner surface is simple squamous. allows light into the eye. focuses
cornea
large collagen fibers= white, smaller with low H2O content= transparent
fibrous
transplant for fibrous
EZ to access/remove. avascular, decreased immune activity
middle tunic layer
vascular
what does the vascular tunic contain
BV and melanin pigmanet cells
order of arteries in vascular tunic
internal carotid artery
ophthalmic artery
short cililary arteries
thin membrane
choroid
ring and processes, attached to lens by suspensory ligaments
choroid body
produce aqeous humor
ciliary processes
what contains smooth muscles and act as a sphincter
choroid body
contract to change shape of lens=
focus
colored portion of eye
iris
contracts pupil to regulate amount of light entering eye
iris
outer muscle fibers-radial= dilate
dilator pupillae
central muscle fibers-circular=constrict
sphincter papillae
inner posterior eye. retina is what tunic layer
nervous
3 neuronal layers are
ganglion, bipolar, photoreceptor cells
pigmented simple cuboidal epithelium
outer pigmented layer
responds to light
contains photoreceptors: 120 million RODS-low liht
6-7 million cones- bright light
inner neural layer
rods is bright or low light
low light
cones is bright or low light
bright light
what do you use to examine retina
use ophthalmoscope
small yellow spot, fovea centralis (center)- most focus (cones)
greatest visual acuity (direct vision)
macula lutea
white spot, central retinal artery in and central retinal vein out of the eye
where optic nerve exists eye
no photoreceptors=blind spot
optic disc
no photoreceptors=
blind spot
nicking of retinal veins where abnormal pressure arteries cross over
hypertension
assiciated with hydrocephalus
increased CSF pressure
increased csf pressure may cause
optic disc to swell causing papilledema
opque lens. not see well at night, halos around lights
cataracts
how do you treat cataracts
surgically remove lens and replace with artificial lens
cotton wool spots-opque fluffy white patches, due to ischemia in retinal nerve
diabetic retinopathy
what are the eye chambers
anterior, posterior, virteous
where is the anterior chamber of the eye
between cornea and iris
what is the anterior chamber filled with
aqueous humor
what does the aqueous humor maintain
intraocular pressure and eyeball shape
condition where there is increased IOP
glaucoma
what provides nutrition to avascular cornea
anterior chamber
what is aqueous humor made by
ciliary processes, returned to circulation via scleral venous sinus
where is the posterior chamber
between iris and lens
what is the virteous chamber filled with
viteous humor
what chamer maintains IOP, shape of eye, holds len and retina in place and has slow turnover
vitreous chamber
what chamber helped with refraction of light
vitreous
pathway in which the eye function
light converge-> cornea to aqueous humor thru pupil-> lens thru vitreous humor-> retina
what does the retina contain
photoreceptors (rods and cones)
what is an eye function
it converts light energy into AP and APs sent to brain along the optic nerve
what is an accommodation
changes the shape of lens to focus on object close or distant
focus in front of retina; see close, distance blurred
eye becomes too elongated; nearsighted; correct with concave lens to diverge light
myopia
4-8 radiating cuts in cornea, cornea flattens, eliminates myopia
issues with visual acuity, glare
radial keratotomy
laser procedure where thin part of cornea cut away to make cornea less convex. better results
LASIK
focus behind the retina; see distance, close is blurred
eye becomes too short, lazy; farsighted; correct with convex lens to converge light
hyperopia
old vision; unavoidable degeneration of accomodation of eye
presbyopia
when does presbyopia start
mid 40s
what causes presbyopia
if you read a lot
how do you prevent presbyopia
use bifocals or prorgressive lenses if need to compensate for close or distant vision
irregular bulge or cornea or lens
astigmatism
light not focused on a singple point but instead is
blurred
how do you correct astigmatism
glasses with opposite curve gradient
if the astigmatism is irregular is it easy or hard to correct
hard
color blindess is
color vision deficiency
color blindness is a dysfunction of
1 or more of 3 photopigments in color vision
if 1 pigment is dysfunctinal and the other two are ok what is it called
dichromatism
dichromatism=
red-green color blindness
ratio of males affected by color blindness
1 in 12 males
ratio of females affected by color blindness
1 in 200
color blindess is x linked recessive that affects
males
are females carriers for color blindness
yes
what chromosome is mutated in blue-yellow color blindess
chromosome 7
monochromatism =
no color
as we age what happens to color blindness
ability to distinquish colors degrades naturally as we proceed to old age
color blindness is also due to
illness, physical or chemical damage to the eye, optic nerve, brain parts or med toxicity
adaptation for light to dark
5 minutes to start, accomodate within 30 minutes
adaptation for dark to light
(see white), 1 minute to start; accomodate in 5-10 minutes
3D and depth perception is what
stereoscopic vision
overlapped area in stereoscopic vision means
seen by both eyes at same time
what does binocular vision give us
depth perception as 2 eyes from diffenet angles
ability to see in low light conditions, impaired rod function; prolonged vitamin A deficiency causing degeneration. not function in dim light
night vision
rabbits and pigeons have what kind of eyes and results in what
lateral w little overlap so less depth perception
whats an emergency situation in the ey
retinal detachment
what is retinal detachment
layers separate and virteous humor flows between them and that results in permanent blindness
is there nutrition from bvs in retinal detachment
no
causes of retinal detachment
traume, head jerk in opposite direction,
MVA: painless process
risk factors for retinal detachment
> age 50, hx retinal detachment, FH of retinal detachment, xs myopia, prior eye surgert, eye disease
dx for retinal detachment
retinal exam, ultrasound
S&S for retinal detachment
sudden flashes of light, floaters, see spots, sensitive to light, blurred vision, unable to see dim light, temporary loss of vision in 1 eye, tunnel vision or visual loss
treatment for retinal detachment
laser surgery, cryosurgery