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23 spring: med surg > Test 2: lecture 29 lens > Flashcards

Test 2: lecture 29 lens Flashcards

1
Q

The transparent structure inside the eye that focuses light rays onto the retina.

A

lens

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2
Q

phako-

A

lens

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3
Q

what side of the lens will have epithelial cells

A

anterior

during gestation cells are pushed forward

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4
Q

congenital cataracts are located where in the eye?

A

nucleus/center

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5
Q

secondary lens fibers form at the — and move —

A

equator

inward- new layers are formed around primary fibers (onion)

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6
Q

lens is held in place by

A

zonular fibers attached to ciliary body processes

lie in patella fossa of the vitreous

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7
Q

epithelial cells — on the lens are the thickest

A

anterior

cells elongate and loose nucleus and organelles at equator

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8
Q

epithelial cells form a Y at what part of the lens

A

anterior

will have inverted Y at posterior of lens

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9
Q

the lens is surrounded by —

A

elastic acellular capsule

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10
Q

new layers of lens fiber are formed at the —

A

equator

older fibers are pushed toward the center

equator: is a frquent site for aquired cataracts

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11
Q

what part of the lens can you see with split lamp

A

capsule(anterior lens)

nucleus

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12
Q

lens is made of soluble proteins (—) and insoluble proteins (—-)

A

cyrstallins (85%)
decreases with age

albuminoid (15%)
increases with age

34% of lens is protein, 65% is water

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13
Q

what type of protein in the eye will decrease with age?

A

soluble (cyrstallin)- can leak out over time

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14
Q

how does lens get energy

A

anearobic glycolysis

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15
Q

nuclear sclerosis of lens will cause —

A

blue-whitish- but can still see through it

normal aging process
caused by change in protein composition and packing of lens fibers

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16
Q

issue with lens

A

nuclear sclerosis

blue-whitish- but can still see through it

normal aging process
caused by change in protein composition and packing of lens fibers

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17
Q

Any opacity of the lens or its capsule

A

cataract

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18
Q

3 type of age of onset cataracts

A

Congenital: present at birth

Juvenile (developmental): from birth to middle age (dog:~ 6 years)

Senile (age-related): (dog > 6 years)

19
Q
A
20
Q
A

inverted Y= back of eye

posterior polar/subcapsular cataract

21
Q

what type of catarct

A

incipient

small- less then 10-15% of lens
do not impair vision
can still see back of eye
mat be located at the equator- easier to see if you dilate pupil

22
Q

incipient catarct take up — % of the eye and — vision

A

10-15%
do not impair vision
can still see back of eye

can be found at equator- easier to see if you dilate eye

23
Q

— cataract is Any degree of lens opacity that is more than incipient but less than complete

A

immature/incomplete

can impair some vision, but not total blindness
can still see back of eye

24
Q
A

mature/complete catarct

complete opacity- total blindness- can not see back of eye

25
Q

mature cataract do what to the eye

A

complete opacity of lens
total blindness- can not see back of eye

26
Q
A

hypermature/resorbing cataract

27
Q

what happens to lens with hypermature cataract

A

becomes smaller as lens is liquefied

anterior lens capsule becomes wrinkled
can see tapetal reflection
can cause uveitis
total resorption can lead to dissapearance of opacities

28
Q

hypermature cataract will cause the — to become wrinkled and can cause lens-induced —

A

anterior lens capsule
uvelitis (phacolytic uveitis)

29
Q

hypermature cataract will cause resorption that will do what to opacities?

A

appear crystallized and then over time will dissolve/liquify opacities

30
Q

morgangnian cataract is a form of — cataract in which the nucleus —

A

hypermature

sinks ventrally in a fluid cilled capsular bag

often associated with len-induced uveitis

31
Q

what type of cataract

A

morgagnian

A form of hypermature cataract in which the nucleus sinks ventrally in a fluid-filled capsular bag.

Often associated with lens-induced uveitis.

32
Q

what are the two major causes of cataracts

A

most are genetic

metabolic (DM)

33
Q

how does Diabetes cause cataract

A

excess glucose can not be broken down by hexokinase

lens will use aldose reductase to create sorbitol which will cause water to enter lens

can occur in 24hrs!

34
Q

cararact caused by

A

diabetes

excess glucose broken down by aldose reductase to form sorbital which pulls water into the lens and swells fibers

intumescent cataract- can occur in 24 hrs!

35
Q

besides genetics and DM what else can cause cataract

A

secondary to other ocular disorder: uveitis, glaucoma
trauma: lens perforation
age related: UV exposure, decrease in antiocydant activity in the lens
nutritional: low arginine
toxic: DMSO

36
Q

how to treat cataracts

A

medical: antioxydants, anti-inflammatory, mydriatic drugs

surgical: Extracapsular cataract extraction (ECCE), Phacoemulsification

37
Q

two surgical treatments of cartaracts

A

Extracapsular cataract extraction (ECCE)

Phacoemulsification

38
Q

tremor of the lens

A

phacodonesis

39
Q

tremor of iris

A

iriododonesis

40
Q

clinical signs of lens luxation

A
  • tremor of lens and iris (phacodonesis, iridodonesis)
  • increased or decreased anterior chamber depth, depends of how lens moves
  • increased IOP
  • aphakic crescent
  • corneal edema
  • uveitis
  • vitreous syneresis (liquefaction)
41
Q

primary cause of lens luxation

A

defect in zonules

ADAMST17 mutation- terriers, spaniels, sharpeis

42
Q

secondary causes of lens luxation

A

glaucoma, uveitis, intraocular tumor, trauma

43
Q

— lens luxation is an ocular emergency because it —

A

anterior

risk of acute glaucoma- within 24 hrs can increase IOP

intracapsular lens extraction

44
Q

how to treat anterior lens luxation

A

intracapsular lens extraction

23 spring: med surg (60 decks)

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