- congenitally small lens - can visualize lens equator and zonules - most common disease of lens - does NOT need treatment

Lens and Cataract Flashcards by Ashley Caprio

primary function of the lens

accommodation

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mechanisms of lens transparency

nonpigmented
avascular
precise organization of fibers
few organelles
relatively dehydrated
precise crystalloid protein ratios

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Y suture?

can see with cataracts. each suture extends 1/3 the way around the lens so a Y is formed in the center of the lens (usually too clear to see)

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lens fibers are produced …..

Fibers are compacted in the center of the lens (lens nucleus) This density becomes apparent as _____ ______.

continually throughout life!

Nuclear Sclerosis

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Nuclear sclerosis is
\_\_\_\_\_
\_\_\_\_\_
\_\_\_\_\_
where Cataract is not.

bilateral/symmetric
in the center always
doesn’t block tapedum or vision

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It can be difficult to correctly diagnose lens disease without ______.

mydriasis

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How does cataract affect the pupillary light reflex?

it doesnt

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microphakia

congenitally small lens
can visualize lens equator and zonules
most common disease of lens
does NOT need treatment

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What part of the lens should you never be able to see?

equator

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must differentiate a subluxated lens with a ?

microphakia (small lens)

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spherophakia

frequently accompanies ____?

congenitally round lens

microphakia

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coloboma

flattened area of lens equator

-just needs monitoring

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what is a cataract?

any opacity of the lens
(loss of transparency secondary to disruption of lens fiber cells and their precise anatomic relationship to one another)
(ex/ Protein ratio’s disrupted)
does not always progress

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Incipient cataract

<10% of total lens volume

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immature cataract

11-99% of total lens volume

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Mature cataract

100% of lens is cataractous

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Hypermature cataract

resorption of lens material

Morgagnian cataract

(variant of hypermature) all cortical material has been resorbed leaving behind nucleus (which floats to bottom)
(dont worry about this one)

Areas cataract can be located?

anterior/posterior subcapsular
anterior/posterior cortical
equatorial 
llamellar/perinuclear
Nuclear
Axial

causes of cataracts

hereditary *most common*
senile
systemic disease (DM most common)
....
Trauma (especially penetrating injuries)
Toxins
Electric shock 
Secondary to ocular disease (uveitis **most common cause in cats***
retinal atrophy
persistent pupillary membranes)
Radiation (treating periocular neoplasia)

Pathophysiology of Diabetic cataracts?

Normal glucose is overwhelmed and shunted to the sorbitol pathway, in which the rate limiting step (Aldose reductase) can’t keep up (especially bc dogs don’t have a lot of AR) resulting in a swollen broken, cataractous lens full of sorbitol

what percent of DM dogs get cataracts?

How bad the diabetes is?

85% within 2 yrs

INDEPENDENT of degree of diabetic regulation

Vacuoles indicate

active cataract formation

cataract treatment

surgery only

phacoemulsification US Energy used to break up lens, then implant a new one

All cataracts are associated with some degree of ____ | (all cataracts bigger than incipient have clinically significant __^___.

lens induced uveitis (phacolytic uveitis) *during cataract formation , lens proteins leak across lens capsule causing inflammation, a quicker developing cataract causes more uveitis

Evil PIFVM?

Pre-Iridal Fibrovascular Membrane and Glaucoma (happens with inflammation, so give anti-inflammatories fooorreevveerr) No epithelial membrane, all plugged up.

All cataracts larger than insipient need to be treated with?

topical anti-inflammatory for life to prevent phacolytic uveitis

Phacoclastic uveitis

traumatic disruption of lens capsule -> liberation of lens proteins -> overwhelming uveitis leading to vision loss (50%) -treatment is controversial

Primary lens luxation

TERRIERS | **loss of zonules, often associated with glaucoma**

secondary lens luxation

glaucoma, chronic uveitis (cats and horses), intraocular neoplasia, trauma -treatment is unrewarding

when lens luxates partially through pupil ->

glaucoma, | thats the worst way to luxate

Can use _________ therapy to prevent anterior lens luxation of the second eye after first lens luxates and is removed.

long term miotic therapy

diagnosing lens subluxation

``` vitreous in anterior chamber aphakic crescent Iridodensesis - iris fluttering phacodenesis - lens wiggle abnormal anterior chamber depth visualized lens equator ```

treatment for lens luxation?

miotic therapy to trap lens behind iris lensectomy and glaucoma tx tx for underlying cause

lens is formed from ____ ______ that is placed in position by infolding

surface ectoderm

the lens capsule is much thicker ____ than _____

anteriorly than posteriorly

in cataractous eye, there is an increase in ____ proteins and a decrease in ____ proteins

increase in insoluble proteins and a decrease in soluble proteins

what does it mean when we can see vacuoles within lens?

signs that cataract is being actively produced

what is the normal rate limiting enzyme for glycolysis of the lens ?

hexokinase

what are some consequences of untreated lens inflammation

- glaucoma - retinal detachment - posterior synechiae - keratitis

primary _____ lens luxation is very painful and lens should be removed, while primary ____ lens luxation is not painful and should be treated with miotic agents

anterior is painful, posterior is not