Term
| What are the three primary pathologic conditions of the lens? |
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Definition
-cataract
-lens luxation
-traumatic lens rupture |
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Term
| What is nuclear sclerosis? |
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Definition
| -normal aging change in all species that results from compression of lens fibers within the nucleus of the lens that is always bilaterally symmetrical |
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Term
|
Definition
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Term
| What are cataracts the result of? |
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Definition
| -an alteration in ater, electrolyte, or protein content in the lens and subsequent derangement of the composition or arrangemant of lens fibers |
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Term
| Describe the species predisposition to development of cataracts. |
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Definition
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Term
| What is the most common etiology of cataracts in dogs? Describe its presentation. HOw do we prevent it in the future? |
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Definition
-genetic
-usually bilateral but onset b/n eyes often staggers
-onset is not related to age
-DO NOT BREED |
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Term
| What is the second most common cause of cataracts in dogs? Describe its presentation. |
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Definition
-diabetes mellitus
-rapid, bilateral onset of mature cataracts and blindness |
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Term
| True or FAlse: Just as in dogs, diabetic cats get cataracts. These animals are frequently undiagnosed. |
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Definition
-FALSE, cats do not get cataracts
-TRUE, animals that develop diabetic cataracts are frequently undiagnosed diabetics |
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Term
| How does diaetes cause cataracts? |
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Definition
| -inc glucose in queous => inc glucose in lens => switches to sorbitol pathway => sorbitol cannot diffuse out of the lens which creates an osmotic gradient causing aqueous to move into lens => lens fibers swell and lose their perfect alignment => catartacts |
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Term
| What is the most common cause of catartact in the horse and cat? HOw does this cause cataracts? |
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Definition
-uveitis
-altered aqueous composition with uveitis can affect the nutrition of the lens resultin in mild capsular catartact to a mature cataract |
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Term
| How do we diagnose cataracts? |
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Definition
-dilate the pupils with tropicamide and examine the eyes
-use the tapetal reflection to highlight any opacities inthe lense |
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Term
| Do cataracts interfere with PLRs? |
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Definition
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Term
| What is an incipient cataract? Are they visual? Do they require surgery? |
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Definition
-just barely starting with little islands in the lens
-can easily see the fundus?
-normal vision
-don't need surgery yet |
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Term
| What is an immature cataract? Are they visual? Do they require surgery? |
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Definition
-blanket of cataracts that interferes wtih seeing the fundus but not completely opaque but you can see tapetal reflection
-visual but decreased vision
-ready for surgery! |
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Term
| What is a mature cataract? Are they visual? Do they require surgery? |
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Definition
-completely blocking fundus and no tapetal reflection
-non-visual
-more than ready for surgery! |
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Term
| What is a hypermature cataract? What increased risks do we see with these? |
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Definition
-lens protein starts to liquefy often resultin in a sparkling appearance
-inc risk for lens Ag induced uveitis, zonular rupture, capsular wrinkling, and retinal detachment |
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Term
| Can you still perform surgery on a hypermature cataract? |
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Definition
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Term
| How do we treat cataracts? |
|
Definition
| -surgery: phacoemulsification with intraocular lens implants |
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Term
| As the primary DVM, how do we "treat" cataracts? |
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Definition
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Term
| Why is it crucial that we refer cataracts early? |
|
Definition
-retina can still be visualized eliminating time nad cost for retinal testing
-dec risk of uveitis, glaucoma, and retinal detachmient
-ideal time for surgery can be chosen
-early surgery has a lower complication rate
-owner can plan financially for the surgery |
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Term
| What do we prescribe when a late immature to mature cataract is diagnosed as the primary DVM? |
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Definition
| -topical steroid or NSAID |
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Term
| What causes lens-induced uveitis? |
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Definition
| -inflammation of hte anterior uvea due to exposure to lens protein |
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Term
| Why does the body not recognize lens protein as self? |
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Definition
| -lens protein is sequestered in embryonic development |
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Term
| Why do we give late immature to mature cataracts topical steroids or NSAIDs? |
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Definition
| -alterations in the lens composition can cause leakage of lens protein through the lens capsule => uveitis |
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Term
| What is an anterior lens luxation? |
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Definition
| -displacement of the lens into the pupil or anterior chamber |
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|
Term
| What is a posterior lens luxation? |
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Definition
| -displacement of the lens into the vitrous chamber |
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Term
| What does anterior luxation look like? |
|
Definition
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Term
| What is a primary lens luxation? What are the two primary causes? |
|
Definition
-no concurrent intraocular disease
-genetic degeneration of the lens zonules & age-related degeneration of the lens zonules |
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Term
| Which dog breeds are genetically predisposed to primary lens luxation? |
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Definition
| -Terriers: Jack Russell, Rat, Wireharied Fox, Sealyham, Tibetan |
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Term
| True or FAlse: Seeing the edge of the lens can be normal. |
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Definition
| -FALSE: seeing the edge of the lens IS NEVER NORMAL |
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Term
| What is the term for the visual cue that is pathognomonic for lens luxation? |
|
Definition
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Term
| What class of drug is contraindicated with lens luxation? |
|
Definition
| -anything that dilates the pupil |
|
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Term
| Does primary lens luxation present as bilateral or unilateral |
|
Definition
| -presents as unilateral HOWEVER the other eye is at risk |
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Term
| What are the clinical signs of a primary anterior lens luxation? |
|
Definition
-acute pain
-diffuse corneal edema
-secondary glaucoma |
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Term
| What are the clinical signs of a primary posterior lens luxation? |
|
Definition
-deep anterior chamber
-iris will be concave and have a fluttering movement (iridodenesis) |
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Term
| How do we treat a primary anterior lens luxation? |
|
Definition
-EMERGENCY EMERGENCY
-lense msut be surgically removed
-STILL VISUAL |
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Term
| How do we treat a primary posteriorly luxated lense? |
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Definition
| -may be surgically removed or left in place (treat with a miotic to help prevent anterior luxation/glaucoma) |
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Term
| What are the two major causes of secondary lens luxations? |
|
Definition
-chronic glaucoma: enlargement of globe => stretching and breaking of zonules
-hypermature cataract: shrinkage of lens => stretching and breaking of zonules |
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Term
| Do we remove lens for secondary lens luxations? |
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Definition
| -not usually, these are usually blind eyes anyway |
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Term
| What does a traumatic lens rupture look like? What causes it? |
|
Definition
-white, cloudy material in anteiror chamber
-can occur with perforating corneal trauma |
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Term
| How do we treat traumatic lens rupture? |
|
Definition
-SAME-DAY EMERGENCY REFERRAL
-emergency surgical removal of the lens |
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Term
| If we do not treat traumatic lens rupture early, what is bound to happen? If we do? |
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Definition
-if slow, exposure of the anterior uvea to ruptured lens material causes severe uveitis and secondary glaucoma ending in a blind, painful eye needing enucleation
-if we do, prognosis is good |
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