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
Cataract where lens starts to shrink and reabsorb. Difficult to differentiate from mature
Hypermature
26
Cataract where nucleus liquefies
Morgagnian
27
Cataract present at birth, nuclear
Congenital
28
Cataract that occurs in young dogs. Possibly hereditary
Juvenile
29
Cataract in older dogs. not hereditary
Senile
30
Most common cause of cataracts in dogs. usually bilateral. usually progress to complete vision loss
Genetic
31
Abnormal glucose metabolisim in the lens that causes cataract
Diabetic cataract
32
Rate limiting enzyme for sorbitol pathway
aldose reductase
33
cataracts common in poodles, labs, irish setters
Secondary to PRA
34
lens becomes malnourished and accumulates toxins causing cataracts
Secondary to uveitis
35
Opacity confined to the lens capsule
Capsular cataract
36
Most of the opacity involves cortex directly beneath lens capule
subcapsular cataract
37
cataract between capsule and nucleus
cortical cataract
38
Opacity primarily in the center of the lens. Frequently congenital and nonprogressive
Nuclear
39
cataract where Most involvement in the area of the lens equator
Equatorial
40
Focal, central opacity in the center of the visual axis
polar cataract
41
What is a sign that cataract is actively being produced
when vacuoles are visible
42
Lens induced uveitis
any cataract will cause inflammation
43
leakage of lens proteins through the intact lens capsule
Phacolytic uveitis
44
How should you treat all cataracts larger than incipient in size and for how long
topical anti-inflammatory | rest of life
45
What drugs are generally safe for long term use
NSAIDS
46
What can occur when lens-induced uveitis has not been treated and there is chronic inflammation
secondary glaucoma
47
formation of fibrovascular membrane on the surface of the iris
Pre-iridal fibroVascular membrane
48
Penetrating trauma to the lens capsule disrupts lends fibers, leading to a cataract
Phacoclastic uveitis
49
What is performed prior to cataract surgery
electroretinogram or ocular ultrasound
50
Treatment of choice for lens extration
phacemulsification
51
Subluxation
lens is partially dislocated
52
luxation
lens in completely dislocated
53
are posterior luxations or anterior luxations prefered
Posterior (non-painful)
54
Lens coming forward and being trapped in the anterior chamber
Primary anterior luxation
55
Is primary anterior luxation unilateral or bilateral
bilateral
56
Loss of zonules cause by other intraocular disease
secondary lens luxation
57
What is the most common cause of lens luxation in cats and horses
Uveitis
58
what are the best treatments for primary lens subluxation
lifelong topical miotic therapy | surgical removal of the lens