Test 2: lecture 29 lens

Question 1

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

Answer 1

lens

Question 2

phako-

Answer 2

lens

Question 3

what side of the lens will have epithelial cells

Answer 3

anterior

during gestation cells are pushed forward

Question 4

congenital cataracts are located where in the eye?

Answer 4

nucleus/center

Question 5

secondary lens fibers form at the — and move —

Answer 5

equator

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

Question 6

lens is held in place by

Answer 6

zonular fibers attached to ciliary body processes

lie in patella fossa of the vitreous

Question 7

epithelial cells — on the lens are the thickest

Answer 7

anterior

cells elongate and loose nucleus and organelles at equator

Question 8

epithelial cells form a Y at what part of the lens

Answer 8

anterior

will have inverted Y at posterior of lens

Question 9

the lens is surrounded by —

Answer 9

elastic acellular capsule

Question 10

new layers of lens fiber are formed at the —

Answer 10

equator

older fibers are pushed toward the center

equator: is a frquent site for aquired cataracts

Question 11

what part of the lens can you see with split lamp

Answer 11

capsule(anterior lens)

nucleus

Question 12

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

Answer 12

cyrstallins (85%)
decreases with age

albuminoid (15%)
increases with age

34% of lens is protein, 65% is water

Question 13

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

Answer 13

soluble (cyrstallin)- can leak out over time

Question 14

how does lens get energy

Answer 14

anearobic glycolysis

Question 15

nuclear sclerosis of lens will cause —

Answer 15

blue-whitish- but can still see through it

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

Question 16

issue with lens

Answer 16

nuclear sclerosis

blue-whitish- but can still see through it

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

Question 17

Any opacity of the lens or its capsule

Answer 17

cataract

Question 18

3 type of age of onset cataracts

Answer 18

Congenital: present at birth

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

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

Question 19

Answer 19

Question 20

Answer 20

inverted Y= back of eye

posterior polar/subcapsular cataract

Question 21

what type of catarct

Answer 21

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

Question 22

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

Answer 22

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

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

Question 23

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

Answer 23

immature/incomplete

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

Question 24

Answer 24

mature/complete catarct

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

Question 25

mature cataract do what to the eye

Answer 25

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

Question 26

Answer 26

hypermature/resorbing cataract

Question 27

what happens to lens with hypermature cataract

Answer 27

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

Question 28

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

Answer 28

anterior lens capsule uvelitis (phacolytic uveitis)

Question 29

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

Answer 29

appear crystallized and then over time will dissolve/liquify opacities

Question 30

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

Answer 30

hypermature sinks ventrally in a fluid cilled capsular bag often associated with len-induced uveitis

Question 31

what type of cataract

Answer 31

**morgagnian** A form of hypermature cataract in which the nucleus sinks ventrally in a fluid-filled capsular bag. Often associated with lens-induced uveitis.

Question 32

what are the two major causes of cataracts

Answer 32

most are genetic metabolic (DM)

Question 33

how does Diabetes cause cataract

Answer 33

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!

Question 34

cararact caused by

Answer 34

**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!**

Question 35

besides genetics and DM what else can cause cataract

Answer 35

**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

Question 36

how to treat cataracts

Answer 36

**medical**: antioxydants, anti-inflammatory, mydriatic drugs **surgical**: Extracapsular cataract extraction (ECCE), Phacoemulsification

Question 37

two surgical treatments of cartaracts

Answer 37

Extracapsular cataract extraction (ECCE) Phacoemulsification

Question 38

tremor of the lens

Answer 38

phacodonesis

Question 39

tremor of iris

Answer 39

iriododonesis

Question 40

clinical signs of lens luxation

Answer 40

* 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)

Question 41

primary cause of lens luxation

Answer 41

defect in zonules ADAMST17 mutation- terriers, spaniels, sharpeis

Question 42

secondary causes of lens luxation

Answer 42

glaucoma, uveitis, intraocular tumor, trauma

Question 43

--- lens luxation is an ocular emergency because it ---

Answer 43

anterior risk of acute glaucoma- within 24 hrs can increase IOP intracapsular lens extraction

Question 44

how to treat anterior lens luxation

Answer 44

intracapsular lens extraction