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77 Cards in this Set
- Front
- Back
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The eye is an embryologic extension of what structure?
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the brain
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What does the external eye consist of?
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eyelid, cojunctiva, lacrimal gland, eye muscles, bony orbit (containing fat, blood vessels, nerves, connective tissue)
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What are meibomian glands?
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located in the eyelid and provide oils to the tear film.
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what is the tarsus?
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provides skeleton to the eyelid
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What are the functions of the eyelid?
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distribute tears over the eye surface, limit the amount of light entering the eye, protect the eye from foreign bodies.
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Where is the lacrimal gland?
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the temporal region of the superior eyelid
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how do tears flow?
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over the cornea, into the lacrimal sac via the canaliculi, then into the lacrimal duct and then into the nasal meatus
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what is the function of the lacrimal gland?
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produce tears to moisten the eye
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what are the 6 eye muscles and what are their innervations?
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superior rectus, inferior rectus, medial rectus, inferior oblique (CN III occulomotor)<br />Lateral rectus (CN VI abducens)<br />Superior oblique (CN IV trochlear)
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what is the function/ innnervation of the levator palpebrae?
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elevates and retracts upper eyelid, CN III
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what is the inner eye composed of?
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outer wall: sclear posteriorly, cornea anteriorly<br />middle/uveal layer: choroid posteriorly, ciliary body and iris anteriorly<br />inner layer: retina
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What is the sclera?
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dense, avascular structure that appears as the white of the eye
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what is the function of the sclera?
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to physically support the internal eye structure.
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what are the characteristics of the cornea?
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they are optically clear, have rich sensory innervation, are avascular, have refractive eye power.
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what is the cornea continuous with?
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the sclera
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what makes up the uveal tract?
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iris, cilliary body, choroid
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what is the iris?
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circular, conractile disc that has pigment cells which produce eye color
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What is the central aperture of the iris?
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the pupil- allows light to travel through to the retina.
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what does the ciliary body do?
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makes aqueous humor, attaches to muscles controlling lens accomodation
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What is the choroid?
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the pigmented vascular layer that gives oxygen to the outer layer of the retina
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What structure is the lens?
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biconvex, transparent
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where is the lens located?
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behind the iris
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Where do the fibers that support the lens come from?
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ciliary body
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What does the retina transform light impulses into?
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into electrical impulses that are transmitted back through the optic nerve, optic tract, visual cortex.
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what passes through the optic foramen?
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optic nerve, opthalamic artery and vein
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how is accurate vision achieved?
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by focusing images on the retina by the cornea and lens. binocular vision requires synchronous function of the extraocular eye muscles.
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how is an object perceived in both visual cortexes if one eye is covered?
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if light is cast on both the temporal and nasal side
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where do the nasal retina cross?
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the optic chiasm
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What structures originate from the optic disc?
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optic nerve, central artery and vein
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what is the site of central vision?
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macula or fovea
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when do the eyes develop in gestation?
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first 8 weeks
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what is vision development dependent on?
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maturation of the nervous system
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what is the vision of a term infant?
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hyperopic, visual acuity of less than 20/400, peripheral vision is fully developed but central is not, lacrimal drainage is complete
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when do the lacrimal glands produce full volume of tears?
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2-3 weeks
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when is binocular vision complete?
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3-4 months
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when can an infant differentiate colors?
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6 months
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does the globe of the eye grow as the head and brain of the child grow?
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yes
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when is adult visual acuity reached?
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4 years of age
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do eyes change during pregnancy?
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yes, due to phys and horm changes
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what are the changes seen in pregnancy?
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hypersensitivity, changes in refractory poer, tears have increased lysozyme which may blur vision and create a greasy sensation, mild corneal edema and thickening (3rd trimester)
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why may subconjuctival hemorrhages appear in late pregnancy or labor?
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decreased intraocular pressure, most notably falls in late pregnancy
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what is the major eye change in older adults?
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progressive weakening of accommodation (focusing power)- presbyopia
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what happens to eye by age 45?
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the lens becomes more rigid and the ciliary muscles become weaker.
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what happens to the eye by age 45?
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the lens becomes more rigid and the cilliary muscles become weaker.
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Your lens forms fibers throughout life- what happens over time?
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the old fibers get compressed centrally to form a dense central region that causes loss of clarity of lens and may contribute to cataracts.
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what are cataracts?
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clouding of the lens that can become partially or totally opaque.
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what are cataract risk factors?
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steroid medication, UV light exposure, cigarettes, diabetes, aging
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what does blurred vision indicate?
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a problem with visual acuity
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what does diplopia mean?
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double vision, may be mono or binocular. monocular- optical problem. binocular- alignment problem.
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Retinoblastoma is...
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autosomal dominant
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smoking increases your risk of what?
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cataract, glaucoma, macular degeneration, thyroid eye disease
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what are symptoms of infant eye congenital abnormalities?
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failure to gaze at mother or objects, failure to blink with bright lights or threatening movements.
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inability of one eye to reflect light properly could indicate???
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retinoblastoma or intraocular problem
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what is scotomata?
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area of diminished vision in vision field
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what is amarurosis?<br /><br />
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transient vision loss
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what are symptoms of pregnancy induced by HTN
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diplopia, scotomata, blurred vision, amarosis
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what is concern of topical eye medications in pregnant women?
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may cross the placental barrier
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What happens to the vision of older adults?
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decreased central vision, dry eyes, scleral brown spots, nocturnal eye pain.
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What is nocturnal eye pain a sign of?
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subacute angle closure- glaucoma
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What does visual acuity test?
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ability to see small details, measure of central vision CNII
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how far should the patient be from a snellen chart?
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20 ft
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How is visual acuity recorded?
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fraction: numerator=distance from chart<br />denominator= the avg distance the eye can read (20/200 means that at 20 ft the pt can read what the avg person can read at 200ft)
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What is better visual acuity?
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a higher fraction (20/10; 20/200)
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What is considered legal blindness?
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vision not correctable beyond 20/200
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when do you perform a pinhole test?
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if the visual acuity fraction was less than 20/20
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What does the pinhole test evaluate?
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if refractive error was involved in measuring visual acuity. if the vision improves by one line, then refractive error was involved. the test directs light to the central portion of the lens
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what can modify the results of visual acuity?
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motivation, interest, literacy, intelligence, attention span
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How do you test near vision?
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rosenbaum pocket vision screener
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how far away do you hold the rosenbaum from patient?
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14 in or 35cm
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how do you measure peripheral vision?
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confrontation test
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what lesions usually produce abnormal confrontation test results?
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stroke, retinal detachment, optic neuropathy, pituitary tumor compression at optic chiasm, central retinal vascular occclusion.
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for routine color testing what do you test?
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the ability to see primary colors
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Red testing is helpful in determing what diseases?
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subtle optic nerve disease when visual acuity is about normal, afferent pupillary defect
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What produces the aqueous humor?
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ciliary body- it also controls accomodation
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What layer supplies oxygen to the outer layer of the retina?
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the choroid layer
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Where do fibers located on the nasal retina decussate?
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the optic chiasma
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what is anisocoria?
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inequality of pupillary size
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