Lens Flashcards
Anatomy
Anterior and Posterior Capsule Equator Nucleus Cortex Zonules
Vascular or Avascular
Avascular
nourishment comes from where
glucose in aqueous humor
Function
refraction - bends light towards retina
cause of nuclear sclerosis
normal aging change around 7 years in dogs
what is a cataract
any opacity of the lens or its capsule
cataract stages
incipient
immature
mature
hypermature
incipient cataract
<15%, tapetal reflex, good vision
immature cataract
15-90%, tapetal reflex, vision
mature cataract
100% opacity, no tapetal reflex, blind
hypermature
lens fibers resorbing, sparkly appearance, wrinkling of lnes capsule, blind, possilbe lens induced uveitis
causes of cataracts
inherited diabetes uveitis nutritional trauma toxins hypocalcemia radiation therapy
cataract treatment
flurbiprofen, diclofenac - topical nsaid reduce inflammation prevent uveitis
topical NSAIDs
flurbiprofen & diclofenac
how often do you give NSAIDs to prevent uveitis with cataracts
BID
what test do you perform before phacoemulsification
electroretinography
most common cause of cataracts in dogs
inherited
most common cause of cataracts in horses and cats
uveitis
how does diabetes cause cataracts
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
what toxins cause cataracts
ketoconazole
retinal degeneration oxidative species
why dont diabetic cats get cataracts
dont have aldose reductase pathway
what can diabetes intumescent cataract lead to
glaucoma - intumescent cataract can cause iris plane to move forward crowding the iridocorneal angle
nuclear sclerosis vs cataract
nuclear sclerosis can see tapetum reflection through opacity and has an opaque center to the lens
what causes lens instability
tearing/breakdown of zonules: hereditary hyper-mature cataracts chronic glaucoma/ buphthalmic globe uveitis intraocular neoplasia trauma
