Eye Intro

Question 1

What is refraction?

Answer 1

the bending of light; images are brought to a focus on the retina by the structures of the eye

Question 2

What structures refract light to form images?

Answer 2

#1 cornea
#2 lens: fine tunes

Question 3

What happens with refraction in old age?

Answer 3

cilliary m stops working, lens can’t accommodate

Question 4

what measures refractive power?

Answer 4

diopters= inverse of the lens focal length in meters; positive magnify (convex) and negative minify (concave)
ex. 1 diopter is a lens with a 1 m focal length
3 diopters is a lens with a 1/3 m focal length

Question 5

how to spectacles with a + diopter affect eye?

Answer 5

shorten the eyes focal length to account for a shorter eyeball (hyperopia)

Question 6

how to spectacles with a - diopter affect the eye?

Answer 6

lengthen the focal length to account of a longer eyeball (myopia)

Question 7

what is myopia? how do you treat it?

Answer 7

nearsightedness: objects up close seen clearly, objects far away are blurry. Treat with a concave lens: have - diopter to lengthen focal length to account for a longer eyeball

Question 8

What is the problem with myopia?

Answer 8

eye ball is too long or too curved; light is refracted to make a image before it reaches the retina

Question 9

What is problem with hyperoria?

Answer 9

Fat lens; increased focal length creates picture behind fovea

Question 10

how do hyperopic and myopic lenses compare?

Answer 10

hyperopic: short and fat
myopic: long and skinny

Question 11

how does a concave lens work?

Answer 11

diverges light to extend its focal length

Question 12

List motor control of eye.

Answer 12

oculomotor, abducens, and trochlear nerves

Question 13

what is included in autonomic motor control of the eye? how does it effect the eye?

Answer 13

ciliary ganglion; causes ciliary body to squeeze the lens (increasing diopters.. decreasing focal length) and constricts pupil

Question 14

what is the near reaction?

Answer 14

pupillary constriction when you focus on a near object (ciliary ganglion)

Question 15

when the eye is relaxed what distance is it best for viewing? near or far?

Answer 15

far; the muscles contract to accommodate for near vision

Question 16

how do anticholinergics effect the eye?

Answer 16

inhibit pupillary constriction; inhibit lacrimation

Question 17

how does clouding of the aqueous, vitreous, and lens affect light passage through the eye?

Answer 17

normally it is clear for accurate light passage; clouding results in poor vision, this cannot be corrected with lenses

Question 18

why do you test with glasses for best corrected vision?

Answer 18

because eye is cloudy and lenses won’t help fix it

Question 19

what happens with DM when sugar is high? will the pinhole test correct it?

Answer 19

???

Question 20

How is the retina structured?

Answer 20

inside out; neural layers superficial to photoreceptors

Question 21

Can people have visual field defects and not realize it?

Answer 21

yes, the brain interpolates data to compensate for blind spots

Question 22

what is the pathway for circulation of aqueous humor?

Answer 22

• ciliary body
• posterior chamber
• anterior chamber
• trabecular meshwork
• canal of schlemn

Question 23

what makes aqueous fluid?

Answer 23

ciliary body

Question 24

what is the Vitreous?

Answer 24

Clear jelly-like substance that fills the eye from the lens to the back of the eye.

Question 25

what is the difference between open and closed angle glaucoma?

Answer 25

Open: chronic, more common, canal of schlemm clogged
closed: acute, pressure forces angle/canal opening shut so no reabsorption is possible

Question 26

what is EOM (extra ocular muscle) testing used for?

Answer 26

to reveal cranial nerve dysfunction or peripheral problems with musculature (ex. entrapment)

Question 27

what is the normal cup to disk ratio?

Answer 27

1:2

Question 28

where is the neuroretinal rim?

Answer 28

between cup and disk borders

Question 29

what is the sclera ring?

Answer 29

border of optic disk

Question 30

Congested optic nerve head, protruding anteriorly towards interior of eye, with blurred margins, and poorly seen vessels is signs of?

Answer 30

chronic papilledema; caused by increased IOP

Question 31

what is AV nicking?

Answer 31

arteriovenous nicking is when a small artery crosse a vein putting pressure on it, causing it to swell on either side of crossing

Question 32

layers of visual reception from ganglion cell later to migrant membrane?

Answer 32

• axons of rentinal ganglion cells
• ganglion cell layer
• bipolar cell layer
• layers of rods and cones
• pigment epithelium
• pigment membrane

Question 33

what vision is lost with a optic nerve lesion in right eye?

Answer 33

right eye vision

Question 34

what vision is lost in chiasmatic lesion?

Answer 34

temporal vision (bitemporal hemianopsia)

Question 35

what vision is lost in left eye optic tract lesion?

Answer 35

nasal vision in left eye; temporal vision right eye

Question 36

where would the deficit be for posterior chiasmatic lesion?

Answer 36

contralateral vision loss; (contralateral homonymous hemianopia)

Question 37

where would the deficit be for anterior chiasmatic lesion?

Answer 37

entire vision loss in one eye

Question 38

where would the deficit be for visual cortex lesion?

Answer 38

homonymous contralateral hemianopia

Question 39

where would the deficit be for lateral geniculate lesion?

Answer 39

Two layers: parvocellular and magnocellular.

Lesions of parvocellular layers disrupt the processing of color and fine detail.

Lesions of the magnocellular layers disrupt the detection of fast moving stimuli.

Question 40

where would the deficit be for chiasmatic lesion?

Answer 40

ipsilateral temporal vision loss

Question 41

what does the lateral giniculate do?

Answer 41

relays info to primary visual cortex via optic radiation

Question 42

where would the deficit be for optic radiation?

Answer 42

homonymous contralateral hemianopia