eye Flashcards
1
Q
eye
A
- hollow sphere
- 2.5cm 1in in diameter
2
Q
lens
A
- behind pupil & iris
- contains numerous layers of protein fibers arranged like onion layers
- lens normally perfectly transparent
- lens cloudiness=cataract - age related/traumatic
- enclosed by clear connective tissue capsule
- held in place by suspensory lig
3
Q
interior eyeball
A
- contains large cavity
- divided into 2 smaller cavities by lens(anterior, posterior)
4
Q
anterior cavity
A
-lies behind the cornea
-filled w/watery fluid (aqueous humor)
intraocular pressure result of aqueous humor
-if inadequate drainage, glaucoma (increased pressure) - can be traumatically induced
5
Q
posterior cavity
A
- lies behind the lens
- contains jellylike substance (vitreous humor)
- keeps eyeball from collapsing & holds retina flushed against interior wall
6
Q
bony orbit
A
-encases eye
7
Q
orbital margin composition
A
- frontal bone: supraorbital margin
- zygomatic&part of frontal bone: lateral orbital margin
- zygomatic&maxillary bone: infraorbital margin
8
Q
orbit composition
A
-frontal(anterior)&sphenoid(posterior): superior aspect
-maxillary, zygomatic, palatine: floor
-thin ethmoid: medial wall
thick zygomatic&frontal: lateral wall
-superior orbital fissure: opening btwn lesser & greater wings of sphenoid(allows passage of cranial nerves& eye vessels
-posterior aspect orbit: optic canal allows optic nerve to reach brain
9
Q
anterior surface of eye
A
- protection: eyelids, eyelashes, conjunctiva
- conjunctiva: membrane that lines eyelids & external surface of eye, secretes mucus to lubricate external eye& reduce friction at eyelids
- lacrimal glands located above lateral ends of eyes, continually releases tears across surface of eye through small ducts
- lacrimal ducts locates at medial corners of eyes, serve as drains for moisture from eyes
- ducts funnel moisture into lacrimal sac then into nasal cavity
10
Q
outer tunic
A
- sclera (fibrous tunic)
- thick, white connective tissue (whites of eye)
- central anterior sclera transparent allow light enter eye (cornea)
11
Q
middle tunic
A
- choroid (vascular tunic)
- highly vascularized
- anterior choroid continuous w/cilliary body & iris(colored part of eye)
- central opening: pupil
- iris controls size of pupil, regulates amt light entering eye
- uvea: choroid, ciliary body, iris collectively
12
Q
internal tunic
A
- retina
- primary function: image formation
- extends posteriorly from ciliary body
- contains light sensitive photoreceptor cells
- rods/cones: dendrites of photoreceptor neurons
- rods: specialized vision in dim light, discriminates btwn different shades of dark & light, shapes, movement
- cones: specialized color vision, visual acuity(sharpness of vision)
- cones concentrated mostly in central fovea(small depression in center macula lutea)
- macula lutea: central portion retina, yellow area great concentration cones, few blood vessels
- axons of neurons pass small area of retina (optic disk), exit as optic nerve to brain
- no photoreceptors in optic disc(blind spot)
13
Q
movement of globe
A
-controlled by 6 muscles
14
Q
4 rectus muscles
A
- superior rectus: moves eye upwards
- medial rectus: moves eye to midline
- lateral rectus: moves eye away from midline
- inferior rectus: moves eye downwards
15
Q
2 oblique muscles
A
- move eye diagonally relative to muscles orientation
- inferior oblique moves eye upward & laterally
- superior oblique moves eus downward & medially
16
Q
visual acuity
A
- measures w/ Snellen chart
- 20/20 vision: read the letters on 20ft line from 20 ft away
- visual range: 210 bilaterally, 75 up
- myopia(nearsightedness): lens puts focus point in front of retina, too near lens
- hypermetropia(hyperopia/farsightedness): lens puts focus point behind retina, too far lens
- astigmatism: abnormal curvature of cornea, light rays passing through portion of cornea not focus on retina properly
- amblyopia(lazy eye): cortical suppression, occurs in children, eye doesn’t focus well so begins to list to one side(wander), treatment: patch good eye force use bad eye
17
Q
evaluation of eye
A
- complet history: location & description symptoms
- immediately assess visual acuity
- inspection requires observation of periorbital discoloration, swelling, ecchymosis, deformity, presence foreign body
- note pupil size/shape
- should be round&equal on both sides, reactive to light
18
Q
hyphema
A
- blood in anterior chamber of eye
- be able to see level of blood
- 8ball hyphema: implies entire anterior chamber filled w/ blood
19
Q
subconjunctival hemorrhage
A
- leakage superficial blood vessels
- get res in whites of eyes
- usually benign, but may conceal underlying pathology
- dark spot on sclera: concern, could be inner tissue of eye bulging outward
20
Q
orbital fracture
A
- occur with blow to eye by object larger than eye
- force will be transmitted to orbit resulting in fracture(blow out fracture)
- fracture floor, inferior rectus can become trapped and can not look upward, will get diplopia(double vision) when try to look upward
- examiner not see involved eye raise as subject looks up
- fracture of medial wall of orbit may not be apparent until subject blows nose, get air escaping into tissue surrounding eye
21
Q
corneal abrasion
A
- scratch on cornea
- cause: direct force, foreign object
- subsequent blinking cause pain & sensation of something in eye
- eye produce tears in effort to wash foreign object away
- treatment is generally eyepatch 24 hrs to allow healing
- must prevent eyelid margin from rubbing over abrasion every time blink
22
Q
iritis
A
- inflammation of iris
- traumatic or infectious
- marked sensitivity to light, pupils may not be equal
23
Q
detached retinal
A
- cause: jarring blow to head
- vitreous humor seep btwn retina & choroid, interrupting nervous connection to optic nerve
- flashes of light, haloes, blind spots
24
Q
ruptures globe
A
- most catastrophic injury to eye
- rupture of sclera w/ spilling of contents
- tears posteriorly not visible
- pain, loss of vision, swelling
- globe may appear disoriented & deep
25
Q
conjunctivitis
A
- usually infectious
- viral or bacterial, very contagious
- eye burn, itch, eyelids stuck together with matter in mornings
- usually viral w/ watery discharge, requires symptomatic treatment
- bacterial may have yellow/green discharge (pink eye), requires antibiotic eyedrops
- chemical etiology, treatment immediate prolonged eye washing with running fluid
