Lens And Vitreous

Question 1

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

Answer 1

Lens zonules

Question 2

What is nuclear sclerosis?

Answer 2

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

Question 3

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

Answer 3

Presbyopia

Question 4

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

Answer 4

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

Question 5

What is a cataract?

Answer 5

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

Question 6

What are the possible locations of cataracts??

Answer 6

Anterior or posterior capsular

Anterior or posterior subcapsular

Anterior or posterior cordial

Equatorial

Nuclear

Question 7

How can you determine the location of a cataract?

Answer 7

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

Question 8

What are the stages of maturation of a cataract?

Answer 8

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

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

Question 9

What stage is this cataract?

Small opacity
Tapetal reflection visible
Does not significantly interfere with vision

Answer 9

Incipient

Question 10

What stage of cataract is this?

Tapetal reflection still visible
Variable effect on vision

Answer 10

Incomplete

Question 11

Stage this cataract

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

Answer 11

Compete cataract

Question 12

Stage this cataract

Lens decreases in volume and same size capsule

Capsule wrinkling
Deep anterior chamber
Tapetal reflection may return

Answer 12

Resorbing

Question 13

Categorize the cataract

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

Answer 13

Intumescent

Question 14

What is the most common etiology of cataracts in dogs?

Answer 14

Inherited

Question 15

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

Answer 15

Inflammatory (eg concurrent/previous uveitis)

Question 16

What is the most common cause of a metabolic cataract?

Answer 16

Diabetes mellitus =. Hyperglycemia

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

Question 17

What is the pathophysiology of diabetic cataracts?

Answer 17

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

Question 18

What can cause a nutritional cataract?

Answer 18

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

Question 19

What is an endogenous toxic cataract?

Answer 19

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

Question 20

T/F: most senile cataracts do not impair vision

Answer 20

True

Question 21

What causes senile cataracts?

Answer 21

Photoodiative injury (UV light)

Question 22

What are possible sequela of cataracts?

Answer 22

Visual impairment

Lens-induced uveitis

Glaucoma

Retinal detachments

Question 23

What are the two forms of lens-induced uveitis?

Answer 23

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

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

Question 24

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

Answer 24

Phacolytic

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

Question 25

Lens induced uveitis is treated how?

Answer 25

Topical steroid or NSAID

Question 26

What is the treatment for cataracts?

Answer 26

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

Question 27

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

Answer 27

Pseudophakia

Question 28

What do you call absence of lens ?

Answer 28

Aphakia

Question 29

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

Answer 29

Luxation/subluxation

Occurs as result to loss of zonular ligament support

Question 30

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

Answer 30

Terriers

Abnormal degeneration of zonular ligaments

Question 31

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

Answer 31

Chronic uveitis

Question 32

Treatment for lens luxation?

Answer 32

Emergency — referral for intracapsular lens extraction

Decrease IOP prior to referral

• mannitol
• carbonic anhydrase inhibitors (dorzolamide)

NO Miotics or mydratics!

Question 33

What is the medical treatment for lens luxation ?

Answer 33

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

Question 34

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

Answer 34

True

Question 35

What are causes of vitreous hemorrhage?

Answer 35

Vasculopathies 
Coagulopathies 
Retinal detachment 
Trauma 
Intraocular tumors 
Congenital abnormalities 
Severe inflammation

Question 36

What is vitreo-retinal dysplasia?

Answer 36

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