Lens Exam 2

What are the layers of the lens?

-capsule

-anterior epithelium

-lens fibers/cortex

-nucleus

What are the traits of the lens?

-transparent

-avascular

-non-pigmented

-protein composition of fibers

-perfectly arranged

What suspends the lens?

zonular fibers extending from ciliary body

What provides nutrition to the lens?

aqueous humor

What is the function of the lens?

-fine-tuning refraction

-focus image on retina

What is a cataract?

disruption of normal lens fiber protein or arrangement

T or F: cataracts alter PLR

False

T or F: cataracts can cause lens induced uveitis

True

What is the main way to assess a cataract?

retroillumination with bright focal source to determine if tapetum is blocked

What are the possible etiologies of cataracts?

-congenital

-inherited

-metabolic

-post-inflammatory

-traumatic

-nutritional

-age

-radiation

-toxicity

-infectious

What is the most common cataract etiology in dogs?

inherited

What are the traits of diabetic cataracts?

-80% prevalence

-usually bilateral

-develops rapidly

-visible suture lines

Uveitis can cause what kind of cataract?

post inflammatory

When do nutritional cataracts commonly occur?

puppies and kittens on milk replacer

What commonly causes cataracts due to toxicity?

ketoconazole

What is an incipient cataract?

-less than 10% effected

-should not significantly impact vision

What is an incomplete cataract?

-greater than 10% but not whole lens

-variable vision deficits

What is a complete cataract?

-entire lens involvement

-visual impairment

What is a resorbing cataract?

-liquefying

-sparkly

-anterior capsule wrinkling

What is an intumescent cataract?

-swollen

-bulging lens

-common with diabetic cataracts

Why is cataract location important?

-give clues regarding etiology

-vision impact

-likelihood off progression

What are the treatment options for cataracts?

-N-acetyl carnosine (controversial)

-lanosterol

-oral nutraceutical

-aldose reductase inhibitor

-address uveitis

-surgery

What kind of surgery is done on cataracts?

phacoemulsification

What is post op care for cataracts?

-essential!

-aggressive topical and systemic anti-inflammatory therapy

-topical lubricant

-oral antibiotic

-e-collar

-frequent rechecks

-long-term tapered meds

What are possible complications to cataract surgery?

-inability to place IOL

-corneal ulceration

-infection

-failure to restore vision

-capsular opacity

-corneal edema

-need for enucleation

What is phacolytic lens induce uveitis?

lens proteins slowly leak through capsule

What is phacolastic lens induced uveitis?

sudden release of lens proteins via capsular defect

What results in lens luxation?

zonular failure

What is primary lens luxation?

inherited

What is secondary lens luxation?

-uveitis

-cataract

-glaucoma

-not trauma

What are treatments for lens luxation/

-address underlying cause

-lensectomy

-transcorneal reduction

-medical management enucleation

What is nucleus sclerosis?

-age related opacity of lens nucleus

-does not significantly impact vision

-does not block tapetum