acquired & congenital lens opacities

characteristics of the lens capsule

elastic membrane

permeable

constantly reproduced

thickest near equator

characteristics of lens cortex

made of densely packed secondary fibers

very little extracellular space

lens physiology

avascular with low oxygen pressure, anaerobic & low energy production which impacts the energy needed for protein synthesis & protection from oxidative damage

new cells enveloping old cells in the lens impacts what?

the refractive gradient & accommodation

compact spaces of inner lens fibers cause accumulation of what

metabolites

oxidative damage to the lens

damage/rupture of cell membranes results in protein aggregation & enzyme inactivation

increase in insoluble proteins & lens hydration

consequences of the aging lens

VA decrease (#1 cause of blindness worldwide)

refractive error change

glare

narrowing of anterior chamber angle

how to measure the impact of a cataract

BCVA

pinhole acuity

potential acuity meter (PAM): projects Snellen onto retina

potential acuity pinhole

brightness acuity test: assesses impact of glare

what slit lamp beam angle is nuclear sclerosis best graded with

30-45 deg angle

nuclear sclerosis grading

trace - slight yellow

1 - yellow

2 - very yellow

3 - yellow orange

4 - orange-brown (brunescent)

what slit lamp beam are PSC & cortical spoking best graded with

retroillumination

what is nuclear sclerosis (NS)

oxidative stress causes homogenous increase in insoluble proteins that results in protein aggregation & accumulation of fluorescent chromophores

characteristics of nuclear sclerosis

dehydration & compaction of nucleus

nuclear yellowing due to chromophore accumulation

light scatter due to denaturation of proteins by free radicals

signs of nuclear sclerosis

VA reduction

myopic shift (due to increased density & stiffness)

where does an aging lens cortex cataract typically begin at

lower nasal quadrant

what does an aging lens cataract begin as

vacuoles between lens fibers that can be transient

what do vacuoles in aging lens cataract cause

denaturation & coagulation of lens proteins

decreased level of amino acids & protein synthesis

increased hydration caused by decrease in potassium

opacification in aging lens cataract results in what

cuneiform (wedge shaped) or radial spoke like opacities

what is the appearance of a mature cortical cataract

mother of pearl appearance

wha is the cause of a mature cortical cataract

swelling of lens due to osmotic effect of aggregated insoluble proteins

what can mature cortical cataract cause

shallow anterior chamber & elevated IOP

what is the cause of hyper mature cortical cataract

leakage of liquified cortex results in capsular wrinkling

what can hyper mature cortical cataract cause

morgagnian cataract (nucleus sinks inferiorly)

shallow anterior chamber & elevated IOP

how can hyper mature cortical cataract lead to glaucoma

lens protein may leak out of lens & trigger a severe non-granulomatous inflammatory response; accumulation of macrophages & proteins in TM can lead to glaucoma

what is the VA of someone with hyper mature cortical cataract

hand motion

light perception

pathophysiology anterior subcapsular cataract

metaplastic change in epithelial cells (become elongated) & migration of adjacent epithelial cells into damaged area realists in plaque-like opacification

what can anterior subcapsular cataract be caused by

angle closure attacks: glaucomflecken

necrosis of lens epithelium

what can posterior subcapsular cataract be secondary to

DM

corticosteroid use

inflammation (anterior/posterior uveitis)

retinitis pigmentosa

atopic dermatitis

pathophysiology of posterior subcapsular cataracts

dysplastic changes in the germinal epithelium; cells become distorted, swollen & unorganized

which vision is affected more in PSC distance or near

near

cause of cataracts in diabetes

increased glucose levels in lens fibers causes accumulation of sorbitol & leakage of water into the lens

which cataracts are most common in diabetes

PSC & cortical

characteristics of Wilsons disease Sunflower cataract

copper deposits in central lens with stellate processes

located under anterior capsule

what cataract does chlorpromazine cause

stellate anterior subcapsular cataract

what is the most common unilateral cataract in young people

traumatic cataract (rosette)

what is vossius ring

pigment imprint from pupillary ruff onto anterior lens capsule

what is glassblower's exfoliation cataract

true exfoliation of anterior lens capsule

pseudoexfoliation increases the risk of what

glaucoma

cardiovascular morbidity

causes of ectopia lentis

trauma

marfan syndrome (bilateral, superotemporal)

pseudoexfoliation

homocystinuria (bilateral, inferonasal)

high myopia

lens anatomy

biconvex, acellular, optically transparent structure

capsule is a transparent basement membrane that surrounds lens & is made of collagen

where are mitotic epithelial cells located

anterior lens

where are new fibers generated in the lens

equator & then migrate to anterior & posterior poles meeting at sutures

clinical presentation of congenital lens opacities

family history

poor vision in infants

asymmetry of red reflex (Bruckner testing)

leukocoria

nystagmus

strabismus

delayed development

etiologic evaluations for congenital catarcts

testing for inborn errors of metabolism

evaluation for congenital infection

evaluation for endocrine dysfunction

indications for cataract extraction

total bilateral cataracts

incomplete cataracts with BCVA <20/50, onset of strabismus or nystagmus

what are pts under 6 months old treated with if they have cataract extraction

aphakic CL

cerulean (blue dot) characteristics

multiple, tiny blue dots scattered in the lens cortex

bluish color caused by dispersion of light

nonprogressive

no effect on VA

what is anterior polar cataract

sharply demarcated opacity beneath the anterior lens capsule caused by metaplasia of epithelial cells

characteristics of anterior polar cataract

consists of fibrous CT beneath an intact anterior lens capsule that are sporadic & non progressive

when anterior polar cataract is unilateral what can it cause

amblyopia due to refractive error in the affected eye

what is posterior polar characteristics

sporadic or familial

round discoid plaque that is clearly demarcated form the rest of lens

cause of posterior polar

dysplastic lens fibers that adhere to the posterior capsule associated with persistent hyaloid remnants, posterior lenticonus & persistent anterior fetal vasculature

clinical presentation of zonular (lamellar) cataract

zone around embryonic nucleus becomes opacified

opacity is sharply demarcated

area of lens within & outside the opaque zone is clear

linear opacities like spokes of a wheel run outwards (riders)

decreased VA

nuclear cataract characteristics

bilateral

decreased VA

genetic mutation

can involve entire or portion of nucleus

what are associated abnormalities of nuclear cataract

microphthalmia

nystagmus

strabismus

what is galactosemia

impaired galactose utilization caused by absence of enzyme (must not have galactose products)

what cataract can galactosemia develop

oil droplet cataract

what can oil droplet cataract result in

lenticular myopia

what is sutural cataract

opacity follows anterior/posterior Y sutures of the fetal nucleus that has no effect in VA & is non-progressive

what is a mittendorf dot

posterior capsular remnant of hyaloid artery that has no affect on VA & is non-progressive

what is a epicapsular star

anterior capsule brown stellate opacities that are remnants of embryonic vascular network

what is persistent fetal vasculature

persistence of anterior hyaloid artery & abnormal tissue proliferation (retinal glial cells) caused by failure of fetal hyaloid vasculature to regress

characteristics of persistent fetal vasculature

unilateral

associated with microphthalmia