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Optho > Lens and cataract > Flashcards

Lens and cataract Flashcards

1
Q

How was the lens formed

A

from surface ectoderm that is placed in position by infolding

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2
Q

Is the lens thicker anteriorly or posteriorly

A

anteriorly

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3
Q

Tips of lens fibers meet and form short lines called

A

suture lines

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4
Q

Highly compacted nuclear lens fibers

A

nuclear sclerosis

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5
Q

How can you differentiate nuclear sclerosis from cataract

A

Nuclear sclerosis is transparent and can be seen through with an ophthalmoscope

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6
Q

What percentage of the lens is water

A

65%

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7
Q

Besides water, what is the other main component of the lens

A

Protein

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8
Q

What is the lens completely dependent upon for nutrients

A

the aqueous

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9
Q

Function of the lens

A

focus light rays on the retina to allow optimal image processing and vision

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10
Q

How is focusing of light achieved

A

accommodation

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11
Q

What stabilizes and holds the lens in the center of the eye

A

zonules

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12
Q

Where do zonules attach to the ciliary processes

A

ciliary body

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13
Q

an eye that lacks a lens

A

aphakic eye

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14
Q

Too small of a lens

A

microphakic

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15
Q

too round of a lens

A

spherophakic

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16
Q

What types of proteins increase and decrease with a cataract

A

Insoluble increase

soluble decrease

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17
Q

What must be done in order to examine the lens

A

pupil fully dilated

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18
Q

What effect will a cataract have on PLR

A

none

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19
Q

Congenital absence of normal tissue

A

Coloboma

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20
Q

How does a coloboma of the leans appear

A

flattened region of the equator of the lens

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21
Q

Earliest and smallest cataract you can see

A

incipient

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22
Q

Cataract with more of the lens involved than incipient. can still see tapetal reflection

A

Immature

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23
Q

Cataract that looks solid, opaque, white marble. No tapetal reflection or retinal detail can be seen

A

Mature

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24
Q

With a mature cataract, are PLR’s normal

25
Q

Cataract where lens starts to shrink and reabsorb. Difficult to differentiate from mature

A

Hypermature

26
Q

Cataract where nucleus liquefies

A

Morgagnian

27
Q

Cataract present at birth, nuclear

A

Congenital

28
Q

Cataract that occurs in young dogs. Possibly hereditary

29
Q

Cataract in older dogs. not hereditary

30
Q

Most common cause of cataracts in dogs. usually bilateral. usually progress to complete vision loss

31
Q

Abnormal glucose metabolisim in the lens that causes cataract

A

Diabetic cataract

32
Q

Rate limiting enzyme for sorbitol pathway

A

aldose reductase

33
Q

cataracts common in poodles, labs, irish setters

A

Secondary to PRA

34
Q

lens becomes malnourished and accumulates toxins causing cataracts

A

Secondary to uveitis

35
Q

Opacity confined to the lens capsule

A

Capsular cataract

36
Q

Most of the opacity involves cortex directly beneath lens capule

A

subcapsular cataract

37
Q

cataract between capsule and nucleus

A

cortical cataract

38
Q

Opacity primarily in the center of the lens. Frequently congenital and nonprogressive

39
Q

cataract where Most involvement in the area of the lens equator

A

Equatorial

40
Q

Focal, central opacity in the center of the visual axis

A

polar cataract

41
Q

What is a sign that cataract is actively being produced

A

when vacuoles are visible

42
Q

Lens induced uveitis

A

any cataract will cause inflammation

43
Q

leakage of lens proteins through the intact lens capsule

A

Phacolytic uveitis

44
Q

How should you treat all cataracts larger than incipient in size and for how long

A

topical anti-inflammatory

rest of life

45
Q

What drugs are generally safe for long term use

46
Q

What can occur when lens-induced uveitis has not been treated and there is chronic inflammation

A

secondary glaucoma

47
Q

formation of fibrovascular membrane on the surface of the iris

A

Pre-iridal fibroVascular membrane

48
Q

Penetrating trauma to the lens capsule disrupts lends fibers, leading to a cataract

A

Phacoclastic uveitis

49
Q

What is performed prior to cataract surgery

A

electroretinogram or ocular ultrasound

50
Q

Treatment of choice for lens extration

A

phacemulsification

51
Q

Subluxation

A

lens is partially dislocated

52
Q

luxation

A

lens in completely dislocated

53
Q

are posterior luxations or anterior luxations prefered

A

Posterior (non-painful)

54
Q

Lens coming forward and being trapped in the anterior chamber

A

Primary anterior luxation

55
Q

Is primary anterior luxation unilateral or bilateral

56
Q

Loss of zonules cause by other intraocular disease

A

secondary lens luxation

57
Q

What is the most common cause of lens luxation in cats and horses

58
Q

what are the best treatments for primary lens subluxation

A

lifelong topical miotic therapy

surgical removal of the lens

Optho (13 decks)

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