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Dog & Cat Medicine and Surgery > Lens > Flashcards

Flashcards in Lens Deck (16):
1

What does a spherical lens do?

Relaxes the zonules, and accommodates for closer distances

2

Ovoid lens - how? why?

Tensed zonules - for distance

3

Microphakia - what is it? how does it appear?

Lens is too small, may see the equator of the lens & the ciliary processes/bodies
Micro = small; phakic = lens (greek)

4

Congenital issues with the lens

Microphakia
Lens coloboma (hole in the lens)
Cataract

5

Lens coloboma

Hole in the lens: Not going to be a donut, more like a notch (piece that is missing off of the lens) but this is extremely rare.
Coloboma in greek = mutilated

6

Cataract (what, type, prevalence)

Opaque lens: In the centre if congenital, in the nucleus. Most common congenital abnormality.

7

How do we classify cataracts? (4)

Age of onset
Progression
Location
Causes

8

Cataract - Stages of maturity (5)

– Incipient (growing/emerging)
– Immature or incomplete
– Mature or complete
– Hyper-mature
– Morgagnian (cortex has liquefied and the nucleus moves freely within the lens)

9

Cataract - location (4)

– Capsular
– Cortical
– Nuclear
– Equatorial

10

Cataract - Causes (6)

• Congenital
• Genetic
• Nutritional (lack of arginine)
• Diabetes mellitus (can happen quickly)
• Traumatic
• Uveitis (chronic)

11

Can we medically treat cataracts?

Not successful, but keeps on marketing drops to cure cataracts.
If there is mild to moderate uveitis, you can use NSAIDs.
If there is severe uveitis, go with steroids.
(topical or systemic)

12

What do you do prior to referring for cataract surgery? during surgery? post-surgery?

1. Make sure you have a stable patient (diabetes, ulcers, uveitis all controlled)
2. Do an ERG/Ocular ultrasound to make sure the retina is ok
3. Phacoemulsification, intra-ocular lens implant
4. Watch intra-ocular pressure, wean off/down medications.

13

Nuclear sclerosis (what does it look like? effects? what still works? treatment?)

Lens gets compressed, looks pearly
Night vision can be affected
Still see tapetal reflex, can still do a fundic exam (retina, rental blood vessels, optic nerve)
Don't treat surgically

14

Causes of lens luxation
Primary - 1
Secondary - 3

1. Primary (congenital/genetic)
2. Secondary (uveitis, trauma, chronic glaucoma - eye becomes too big, zonules can pop)

15

Lens luxation positions (3)

Subluxation
Posterior
Anterior

16

Treatment for lens luxation

Treat the underlying cause
Surgically extract the lens right away
Or if you can't enucleate/eviscerate (if you have a blind and painful eye)