Lens And Vitreous Flashcards Preview

RUSVM SAM 2 > Lens And Vitreous > Flashcards

Flashcards in Lens And Vitreous Deck (36):
1

What do you call the suspensory ligaments connecting the ciliary body the the lens equator

Lens zonules

2

What is nuclear sclerosis?

New lens cells/fibers are produced through life, with age central lens fibers become compressed

3

What do you call the loss of accommodative power as nucleus hardens?

Presbyopia

4

How does the lens appear with nuclear sclerosis and how does it differ from a cataract?

Visible accentuation of lens nucleus

Bluish-gray, pearly haze

If there is any light passing through, its a nuclear sclerosis and not a cataract
- does not cause a clinically apparent blindness
-tapetal reflection visible through sclerotic lens
-fundus visible through sclerotic lens

5

What is a cataract?

Any opacity of the lens or its capsule

May interfere with vision
- tapetal reflection and fundus not visible through cataract but may be visible around cataract

6

What are the possible locations of cataracts??

Anterior or posterior capsular

Anterior or posterior subcapsular

Anterior or posterior cordial

Equatorial

Nuclear

7

How can you determine the location of a cataract?

Oblique examination = shine a brigh focal light along the visual axis and examine from oblique angle

Parallax
=anterior opacities move in same direction as eye
=posterior opacities move in opposite direction of the eye
=nuclear opacities appear to remain stationary

8

What are the stages of maturation of a cataract?

Incipient
Immature (incomplete)
Mature (complete)
Hypermature (resorting)

Intumescent (may be complete incomplete) - most often with DM and rapidly progressing cataracts

9

What stage is this cataract?

Small opacity
Tapetal reflection visible
Does not significantly interfere with vision

Incipient

10

What stage of cataract is this?

Tapetal reflection still visible
Variable effect on vision

Incomplete

11

Stage this cataract

100% of lens affected
Tapetal reflection is not visible
Eye is blind

Compete cataract

12

Stage this cataract

Lens decreases in volume and same size capsule

Capsule wrinkling
Deep anterior chamber
Tapetal reflection may return

Resorbing

13

Categorize the cataract

Increased lens size, shallow anterior chamber, separation clefts at Y-suture

Intumescent

14

What is the most common etiology of cataracts in dogs?

Inherited

15

What is the most common cause of cataracts in cats and horses?

Inflammatory (eg concurrent/previous uveitis)

16

What is the most common cause of a metabolic cataract?

Diabetes mellitus =. Hyperglycemia


Sorbitol accumulation in the lens draws in water and causes structural changes in the lens

17

What is the pathophysiology of diabetic cataracts?

Glucose shunted to an alternative pathway

Dogs have high levels of aldose reductase to make sorbitol

Sorbitol build up in lens and pulls in water

18

What can cause a nutritional cataract?

Puppies and kittens fed milk replacements — maybe due to amino acid deficiency

Characteristic perinuclear opacity — usually

Prevented by using milk of dam for the first week of life
Supplant with high quality milk replacer

19

What is an endogenous toxic cataract?

Degenerating photoreceptors release toxic substances into vitreous. —> seen in various degenerative retinal diseases like progressive retinal atrophy

20

T/F: most senile cataracts do not impair vision

True

21

What causes senile cataracts?

Photoodiative injury (UV light)

22

What are possible sequela of cataracts?

Visual impairment

Lens-induced uveitis

Glaucoma

Retinal detachments

23

What are the two forms of lens-induced uveitis?

Phacoclastic: severe form associated with traumatic tears of the lens capsule

Phacolytic: milder form associated with leakage of lens proteins from cataract (more common)

24

What type of lens induced uveitis should you suspect in any red eye with a cataract?

Phacolytic
— results from exposure of immunologically isolated lens protein to the immune system

25

Lens induced uveitis is treated how?

Topical steroid or NSAID

26

What is the treatment for cataracts?

Medical disssolution agents like N-acteylcarnoisne have no proven benefit

Anti-inflammatories - Diclofenac, flurbiprofen, or ketorolac
To treat lens induced uveitis

Surgical— phacoemlsification
High frequency vibrations emulsify cataract and remove it by aspiration through a small corneal incision

27

What do you call the presence of an articular intraocular lens post surgery?

Pseudophakia

28

What do you call absence of lens ?

Aphakia

29

What do you call displacement of themes form its normal position in the patellar fossa?

Luxation/subluxation


Occurs as result to loss of zonular ligament support

30

Primary inherited disorder causing lens luxation is common in what breeds?

Terriers

Abnormal degeneration of zonular ligaments

31

What is the most common cause of lens luxation in cats?

Chronic uveitis

32

Treatment for lens luxation?

Emergency — referral for intracapsular lens extraction

Decrease IOP prior to referral
- mannitol
-carbonic anhydrase inhibitors (dorzolamide)

NO Miotics or mydratics!

33

What is the medical treatment for lens luxation ?

Dilate the pupil with mydratic

Allow lens to fall behind the pupil

Trap the lens posteriorly with miotic —>latanoprost (BID)

Occasionally the lens can be pushed into the posterior segment through the pupil = couching

34

T/F: asteroid hyalosis sis when there are suspended lipid/calcium bodies in the vitreous which is a normal age related change

True

35

What are causes of vitreous hemorrhage?

Vasculopathies
Coagulopathies
Retinal detachment
Trauma
Intraocular tumors
Congenital abnormalities
Severe inflammation

36

What is vitreo-retinal dysplasia?

Liquefied vitreous preciouses to retinal tearing and detachment
—severe forms of rental dysplasia
—giant rentinal tears and detachments