Chapter 13 Eye Flashcards
Name and describe the features of the eye
pupil - opening where light enters eye
Iris - gives color to eyes
sclera - white of eye
cornea - glassy transparent external surface of eye
optic nerve - bundle of axons from retina
what is the purpose of the optic nerve
transmission to brain of external images (sight)
what is the function of eyelids
protect the eye of foreign particles by means of eyelashes (cilia)
sebaceous glands secrete a lubricating oil onto eyelash
describe what conjunctiva is
mucous membrane of eye
lines inside the eyelids to help lubricate the eye with mucus and tears
what does the lacrimal apparatus consist of?
superior and inferior lacrimal glands
lacrimal sac
lacrimal ducts
nasolacrimal duct
strabismus
eye muscle weakness resulting in eyes looking in different directions at same time
esotropia (ST)
eso- = inward -tropia = turned condition
type of strabismus with inward turning of eye
“cross-eyed”
exotropia (XT)
exo- = outward -tropia = turned condition
type of strabismus with outward turning of eye
“wall-eyed”
what is the function of the cornea?
admit and refract light
what is the function of the iris and pupil?
smooth muscle that changes size of pupil to control amount of light entering the eye
what is the function of the lens?
focus light rays onto retina
what are the three layers of the eye?
retina
choroid
sclera
what is the function of the retina?
contains sensory receptors
what is the function of the choroid layer
supplies blood to eye structures
what is the function of the sclera?
tough protective layer of eye
what layer is the cornea a part of?
sclera
what is aqueous humor and where is it found?
watery fluid
found between cornea and lens
what is vitreous humor and where is it found?
semi-solid gel
found between lens and retina
explain what refraction is?
bending of a wave when it enters a medium where its speed is different
ex. light is refracted when it passes from a fast medium (air) to a slow medium (water)
what is the structure on the eye that causes refraction? what does this mean
cornea and aqueous humor
refracts light rays due to slowing of light at the air-cornea interface
immersing cornea under water will eliminate its refractive power because light travels at the same speed through water and aqueous humor
what is the function of the ciliary body?
attaches to lens; pulls on edge of lens which changes shape of lens in order to focus light onto retina
define accommodation
changes the shape of the lens to alter the focal distance of the eye;
the change in lens shape is controlled by ciliary body muscles
describe briefly the travel path of light rays though the eye
cornea aqueous humor pupil lens vitreous humor retina
what are photoreceptors?
sensory receptor cells that detect light rays
where can you find photoreceptors?
within the retina (inner layer of eye)
what kind of color do cones pick up on? when is are they actively used?
color vision
active only in bright light
what kind of color do rods pick up on? when are they actively used?
gray tones
active in dim light
what is another name for macula lutea? what is it’s function and where is it found?
fovea centralis
part of retina responsible for sharp, detailed central vision; contains high concentration of cones
found center most posterior portion of eye
because of refraction, what happens to an image when the optic nerve takes in the information? what corrects this?
image forms upside down
brain take this information and turns it right side up
Emmetropia
emmetr/o = correct, proper -opia = vision condition
state of normal vision
what is the location where the optic nerve leaves the eyeball?
optic disk
what else leaves through the optic disk besides the optic nerve?
retinal blood vessels
there are no rods or cones found at the optic disk, what does this cause within our vision?
blind spot
ophthalmologist
ophthalm/o = eye
doctor who specialized in treatment of eye
optician
opt/o = vision -ician = specialist
person trained in grinding and fitting corrective lenses
optometry
opt/o = vision -metry = process of measuring
medical profession specializing in examining and testing the eyes and prescribing corrective lenses
optometrist
opt/o = vision -metrist = specialist in measuring
doctor of optometry
blepharoptosis
blephar/o = eyelid -ptosis = drooping
drooping eyelid
iridoplegia
irid/o = iris -plegia = paralysis
paralysis of the iris
ophthalmalgia
ophthalm/o = eye -algia = pain
eye pain
ophthalmoplegia
ophthalm/o = eye -plegia = paralysis
paralysis of one or more of the extraocular eye muscles
ophthalmorrhagia
ophthalm/o = eye -rrhagia = abnormal flow condition
bleeding from eye
xerophthalmia
xer/o = dry ophthalm/o = eye -ia = condition
dry eyes
scleromalacia
scler/o = sclera -malacia = abnormal softening
softening of the sclera
photophobia
phot/o = light -phobia = fear
strong sensitivity to bright light
papilledema
papill/o = optic disk -edema = swelling
swelling of the optic disk
myopia
myo- = to shut -opia = vision condition
nearsightedness; distant objects not seen clearly
what can cause myopia?
eyeball being too long;
causes parallel light rays to converge before retina
hyperopia
hyper- = excessive -opia = vision condition
farsightedness;
eye cannot see near points
what can cause hyperopia?
eyeball being too short;
causes light to be focused behind retina
presbyopia
presby/o = old age -opia = vision condition
visual loss due to old age
decreased ability to focus on near objects
astigmatism
a- = without stigmat/o = point -ism = state of
uneven cornea causing blurred vision
light rays do not focus sharply on retina
corneal abrasion
scraping injury to cornea
achromatopsia
a- = without chromat/o = color -opsia = vision condition
color blindness: unable to perceive one or more colors
monochromatism
mono- = one chromat/o = color -ism = state of
unable to perceive one specific color
cataract
damage to lens causing it to become cloudy
glaucoma
glauc/o = gray -oma = mass
increased pressure in fluid of eye which interferes with optic nerve function
explain how vision deteriorates with glaucoma
peripheral vision is reduced
then tunnel vision develops
blindness can ultimately develop
what is the commonness of glaucoma?
20% of adults over age 40
accounts for 15% blindness in America
what qualifies as someone being legally blind
having severely impaired vision;
20/200 acuity (can only see the first row letter E)
macular degeneration
macul/o = macula lutea -ar = pertaining to
deterioration of macula lutea areas of retina
causes central vision loss
pterygium
hypertrophied conjunctival tissue in inner corner of eye
conjunctivitis
conjunctiv/o = conjunctiva -itis = inflammation
inflammation of the conjunctiva; usually from bacterial infection; “pink eye”
hordeolum
purulent (pus) infection of sebaceous gland of eyelid; “stye”
ambly/o
dull, dim
aque/o
water
blast/o
immature, embryonic
blephar/o
eyelid
cycl/o
ciliary muscle
emmetr/o
correct, proper
glauc/o
gray
macul/o
macula lutea
mi/o
lessening
mydr/i
widening
nyctal/o
night
presby/o
old age
stigmat/o
point
uve/o
choroid
vitre/o
glassy
