Lens Flashcards
Where do the lens zonules go from to?
Ciliary processes of the ciliary body to the lens capsule
During development of the lens where does it get its nutrition from?
Hyaloid artery
Where does the lens in an adult get its nutrition from and excrete it’s waste?
Aqueous
What is aphakia?
Absence of a lens
Which breeds can get the inherited form of persistent hyper plastic primary vitreous/ persistent hyperplastic tunica vasculosa lentis?
Staffy
Doberman
New lens fibres causing compression of the lens results in loss of hydration of the lens nucleus. What is this called?
Nuclear sclerosis
Young puppies (few weeks old) can show opacities at the equatorial end of one or more suture lines in the lens. Does this remain in adulthood?
No, disappears within a few weeks
Congenital inherited cataracts are seen in which breeds (4)?
What condition are they normally associated with?
Do they progress?
What is the treatment?
Miniature schnauzer
Cocker spaniel
Golden retriever
WHWT
Microphthalmos
No
Don’t normally need surgery. Twice weekly atropine
Which breeds are predisposed to early developing cataracts?
Are these progressive?
Boston terrier
French bulldog
Staffy
Welsh springer
Yes
Which breeds are affected by posterior polar subcapsular cataract?
Do they progress
Do they normally affect vision?
What shape do they normally take?
Retriever breeds
Siberian husky
Large munsterlander
English and white setters
Progression minimal
No
Triangular/ Y shape
What is Mittendorf’s dot?
Where is it in reference to the suture lines?
Insertion of the hyaloid vasculature on the posterior lens capsule
Ventromedial to the suture lines
Which breeds are prone to getting secondary cataract with PRA?
what age bracket?
English cocker spaniel
Miniature poodles
Middle aged
What is nyctalopia?
Decreased vision in dim light
Does retinal degeneration cause cataracts in cats?
No
What can diabetic cataracts cause?
Which breed is this common in?
Lens rupture and Phacoclastic uveitis
Or phacolytic uveitis
Labs
What can cause cataracts in orphaned puppies/ kittens?
Inappropriate milk substitutes
Which cat breeds can get congenital cataracts?
Where in the lens?
Persian
British short hair
Nuclear
What is the most common cause of cataract in the cat?
Uveitis
When performing phacoemulsification atropine is used 12 and 2h prior to surgery. What condition should this not be used for and what medication should be used instead?
KCS
Tropicamide
What other medication as well as atropine is used 12h prior to phacoemulsification?
Why?
Phenylephrine
Helps dilation
Topical NSAIDs is applied every 30mins 4x 2h prior to phacoemulsification.
What does this do?
Prevents prostaglandin mediated intra operative miosis
Reduces the blood aqueous barrier breakdown
Instead of using atropine in the eye prior to phacoemulsification, what other technique can be used?
Intracameral adrenaline
Sodium hyaluronate, chondroitin sulphate and methylcellulose are examples of what?
Viscoelastics
How long are usually are topical antibiotics used for post phacoemulsification?
7-10days
How long are usually are topical anti inflammatories used for post phacoemulsification?
2-3 months
Topical mydriatics are often used post phacoemulsification for what reason?
Which one?
Stabilise the blood aqueous barrier
Reduce synechia
Tropicamide
Which breeds are predisposed to primary lens luxation (2)?
What age bracket?
Terriers
Border collies
Young- middle aged
What is the word for wobbling of the iris?
Iridodonesis
When using mannitol as an osmotic diuretic, what dose should be used?
Mannitol 10-20%
1-2g/kg IV over 20-30mins
In the lens where are the cells which replicate (metabolically active area)?
Anterior epithelium on anterior surface
Do the lens fibres have nuclei?
Is the lens hydrated or dehydrated?
No
Dehydrated
What is this congenital disorder?
Which breed?
Persistent primary hyperplastic vitreous
Staffy
Doberman
What are lens fibres made up of?
What do these change to in cataracts
Soluble crystallins
Insoluble crystallins
What is the difference between a mature and immature cataract?
Mature cannot get tapetal reflection, immature can!
Which condition is normally associated with intumescent cataract?
What can this cause?
DM
Phacoclastic uveitis
What type of cataract is this (lens is in place!)?
Why does it have this appearance?
Hypermature cataract
Some leaking of lens- phacolytic uveitis
What type of cataract is this?
Morgagnian
What changes do crystallins undergo with ageing that causes opacity?
Oxidative change
Inherited Posterior polar subcapsular cataracts start where?
Breeds?
Around the suture lines
Retriever breeds; labs, golden retrievers
Red & white setter
Munsterlander
Siberian husky
What is the gene mutation for primary lens luxation?
What is the inheritance?
ADAMTS17
Recessive but carriers can get PLL
