Lens

Question 1

Anatomy

Answer 1

Anterior and Posterior Capsule
Equator
Nucleus 
Cortex
Zonules

Question 2

Vascular or Avascular

Answer 2

Avascular

Question 3

nourishment comes from where

Answer 3

glucose in aqueous humor

Question 4

Function

Answer 4

refraction - bends light towards retina

Question 5

cause of nuclear sclerosis

Answer 5

normal aging change around 7 years in dogs

Question 6

what is a cataract

Answer 6

any opacity of the lens or its capsule

Question 7

cataract stages

Answer 7

incipient
immature
mature
hypermature

Question 8

incipient cataract

Answer 8

<15%, tapetal reflex, good vision

Question 9

immature cataract

Answer 9

15-90%, tapetal reflex, vision

Question 10

mature cataract

Answer 10

100% opacity, no tapetal reflex, blind

Question 11

hypermature

Answer 11

lens fibers resorbing, sparkly appearance, wrinkling of lnes capsule, blind, possilbe lens induced uveitis

Question 12

causes of cataracts

Answer 12

inherited
diabetes
uveitis
nutritional
trauma
toxins
hypocalcemia
radiation therapy

Question 13

cataract treatment

Answer 13

flurbiprofen, diclofenac - topical nsaid reduce inflammation prevent uveitis

Question 14

topical NSAIDs

Answer 14

flurbiprofen & diclofenac

Question 15

how often do you give NSAIDs to prevent uveitis with cataracts

Answer 15

BID

Question 16

what test do you perform before phacoemulsification

Answer 16

electroretinography

Question 17

most common cause of cataracts in dogs

Answer 17

inherited

Question 18

most common cause of cataracts in horses and cats

Answer 18

uveitis

Question 19

how does diabetes cause cataracts

Answer 19

hexokinase pathway is overwhelmed glucose is shunted to aldose reducase pathway creating sorbital - creates hyper osmotic gradient and fluid rushes into lens disturbing organization of lamellar fibers

Question 20

what toxins cause cataracts

Answer 20

ketoconazole

retinal degeneration oxidative species

Question 21

why dont diabetic cats get cataracts

Answer 21

dont have aldose reductase pathway

Question 22

what can diabetes intumescent cataract lead to

Answer 22

glaucoma - intumescent cataract can cause iris plane to move forward crowding the iridocorneal angle

Question 23

nuclear sclerosis vs cataract

Answer 23

nuclear sclerosis can see tapetum reflection through opacity and has an opaque center to the lens

Question 24

what causes lens instability

Answer 24

tearing/breakdown of zonules:
hereditary
hyper-mature cataracts
chronic glaucoma/ buphthalmic globe
uveitis
intraocular neoplasia
trauma

Question 25

most common breed to inherit lens luxation

Answer 25

terriers

Question 26

why is anterior lens luxation an emergency

Answer 26

iridocorneal angle blockage leading to glaucoma

Question 27

characteristics of anterior lens luxation

Answer 27

refractive ring
deep anterior chamber
iridonesis
vitreal prolapse
PAIN
corneal edema
uveitis

Question 28

characteristics of posterior lens luxation

Answer 28

deep anterior chamber
iridonesis
vitreous prolapse
uveitis +/-

Question 29

characteristics of subluxation

Answer 29

aphakic crescent
phacodonesis
zonules
+/- vitreous prolapse

Question 30

treatment of lens lux

Answer 30

Latanoprost BID FOREVER

Question 31

procedures for anterior lens lux

Answer 31

couching

intra-capsular lens extraction

Question 32

how does latanoprost work to help lens lux

Answer 32

prostaglandin analog
receptors in iris causing miosis
keeps lens in posterior chamber

Question 33

PLR normal or abnormal with cataracts

Answer 33

should ALWAYS be normal