Acquired Lens Opacities Flashcards
what part of the lens is a permeable, elastic membrane that is constantly reproduced?
capsule
where is the lens capsule the thickest?
near the equator
what part of the lens is made of densely packed secondary fibers?
lens cortex
what part of the lens has very little extracellular space?
lens cortex
is the lens vascular or avascular? does it have high or low oxygen pressure?
avascular with low oxygen pressure
what physiological factors impact the energy needed for protein synthesis & protection from oxidative damage?
highly anaerobic & lower energy production
damage or rupture of cell membranes in the lens results in what?
protein aggregation & enzyme inactivation
oxidative (free radical) damage causes an increase in what?
- increase in soluble proteins
- increase in lens hydration
when new cells envelope old cells, what occurs?
growth in diameter & axial length
when new cells envelope old cells, what does it impact?
refractive gradient & accommodation
what makes diffusion difficult? what happens?
compact spaces of inner lens fibers → metabolites accumulate over time
where are the oldest cells located?
nuclear & inner cortical
what are oldest cells devoid of?
organelles & access to oxygen
what are the most common causes of complicated (secondary) cataracts?
- uveitis
- retinal detachment
- retinitis pigmentosa
acquired cataracts can be associated with what skin disease?
atopic dermatitis
what metabolic etiologies most commonly cause acquired cataracts?
- diabetes
- Wilson’s disease
- myotonic dystrophy
what drugs commonly cause acquired cataracts?
- corticosteroids
- chlorpromazine
what are the 3 morphological classifications of acquired cataracts?
- nuclear
- subcapsular (anterior & posterior)
- cortical
what are the 3 types of cortical cataracts?
- polar
- cuneiform: cortical spoking
- vacuoles
what are the consequences of aging lens?
- VA decrease → #1 cause of blindness in the world
- refractive error change
- increased glare
- shallower anterior chamber
what do you use to measure the impact of a cataract by projecting the Snellen chart onto the retina?
potential acuity meter (PAM)
what is an alternative to the potential acuity meter?
potential acuity pinhole
what is used to assess the impact of glare on visual acuity?
brightness acuity test
nuclear cataracts are best graded with the slit lamp beam at what angle? & focused on which structure?
30-45 degrees to the lens
what grade is a nuclear sclerotic cataract that appears Brunescent?
grade 4
what grade is a nuclear sclerotic cataract that appears yellow-orange?
grade 3
when a nuclear sclerotic cataract is graded as “trace”, what color is it?
slight yellow
cortical spoking is best graded with what slit lamp technique?
retroillumination of the lens
posterior subcapsular cataracts are best graded with what slit lamp technique?
retroillumination of the lens
what would you grade a PSC that is > 3mm?
grade 3+
what size is a PSC when it is graded as PSC 2+?
2-3mm
what would you grade a PSC that is 1-2mm?
PSC 1+
what causes steady gradual changes in the lens after age 40?
oxidative stress
a homogenous increase in insoluble proteins resulting in protein aggregation & accumulation of fluorescent chromophores causes what type of acquired cataracts?
nuclear sclerosis
T/F: nuclear sclerosis is not age-related
false
which age-related cataract presents as dehydration & compaction of the nucleus & nuclear yellowing due to chromophore accumulation?
nuclear sclerosis
in nuclear sclerosis, what causes light scatter?
denaturation of proteins by free radicals
how do nuclear sclerotic cataracts progress?
usually a slow, uniform progression
what impact do nuclear sclerotic cataracts have on visual acuity?
- VA reduction
- increased density & stiffness can lead to myopic shift
which cataract typically begins in the lower nasal quadrant & as vacuoles between the lens fibers that can be transient?
cortical cataracts
which age-related cataract is due to:
- denaturation & coagulation of lens proteins
- decreased level of amino acids & protein synthesis
- increased hydration caused by decrease in potassium
cortical cataracts
which age-related cataracts has opacification that results in cuneiform (wedge-shaped) or radial spoke-like opacities?
cortical cataracts
when cortical cataracts present with vacuoles, what impact does it have on visual acuity?
no impact on VA
what is a common symptom in cortical cataracts? what is it due to?
glare → due to light scatter
what age-related cataract is caused by swelling of lens due to osmotic effect of aggregated insoluble proteins?
mature cortical cataracts
which age-related cataract has a “mother of pearl” appearance?
mature cortical cataracts
what are the sequelae of mature cortical cataracts?
can cause shallow anterior chamber & elevated IOP
what age-related cataract occurs when leakage of liquified cortex results in capsular wrinkling?
hypermature cortical cataracts
in a hypermature cortical cataract, what can happen as a result of the liquified cortex?
nucleus can sink inferiorly
T/F: hypermature cortical cataracts can cause shallow anterior chamber & elevated IOP
true
what impact do hypermature cortical cataracts have on visual acuity? how would you test their visual acuity?
significant VA reduction
- hand motion
- light perception
what structure of the lens cannot be viewed in a dilated pupil with a hypermature cortical cataract?
posterior pole
in hypermature cortical cataracts, what can occur when lens proteins leak out of the lens?
it can trigger a severe nongranulomatous inflammatory reaction
in hypermature cortical cataracts, accumulation of macrophages & protein in the trabecular meshwork can lead to what?
glaucoma
what type of age-related cataracts occur due to metaplastic change in epithelial cells?
anterior subcapsular
in anterior subcapsular cataracts, the epithelial cells become?
elongated
anterior subcapsular cataracts can also be caused by what? what is it called?
angle-closure attacks (glaucomflecken)
angle-closure attacks in anterior subcapsular cataracts are caused by what?
necrosis of the lens epithelium
which type of age-related cataract presents as a plaque-like opacification due to migration of adjacent epithelial cells into the damaged area?
anterior subcapsular cataracts
which age-related cataract is caused by dysplastic change in the germinal epithelium? what happens to the cells?
posterior subcapsular
- cells become distorted, swollen & unorganized
posterior subcapsular cataracts can be secondary to what?
- diabetes
- corticosteroid use
- inflammation
- retinitis pigmentosa
- atopic dermatitis
what impact do posterior subcapsular cataracts have on visual acuity?
it may affect near vision more than distance
in diabetes, what causes an accumulation of sorbitol & leakage of water into the lens?
increased glucose levels
what is also known as a christmas tree cataract?
myotonic dystrophy
in cataracts caused by myotonic dystrophy, are the cataracts nasal, central, or temporal? what color are they? what structure of the lens is it present in?
central, polychromatic, present in the cortex
what is also known as sunflower cataracts?
Wilson’s disease
which metabolic disorder causes copper deposits in the central lens with stellate processes?
Wilson’s disease
where are cataracts due to Wilson’s disease located?
under anterior capsule
T/F: sunflower cataracts cannot resolve with appropriate systemic treatment of the disease
false
in patients with atopic dermatitis, when would they develop cataracts?
2nd-4th decade
are cataracts from atopic dermatitis unilateral or bilateral? how do they progress?
often bilateral & mature quickly
what condition causes a shield cataract, commonly an anterior subcapsular plaque?
atopic dermatitis
in patients with atopic dermatitis with cataracts, what is another presentation? (besides an anterior subcapsular plaque)
stellate posterior subcapsular opacity
corticosteroids most commonly cause what type of cataract?
posterior subcapsular cataracts
which drug induces a stellate anterior subcapsular cataract with granular deposits?
chlorpromazine
what is the most common cause of unilateral cataracts in young individuals?
blunt trauma
what is a pigment imprint from pupillary ruff onto anterior lens capsule called?
Vossius ring
true exfoliation of the anterior lens capsule is caused by what?
heat (infrared radiation) trauma
inflammation such as uveitis, retinal detachment & retinitis pigmentosa can result in which type of cataract most commonly?
PSC
what is a systemic condition that results in fibrillary residue deposits?
pseudoexfoliation
pseudoexfoliation increases the risk of what? & why?
increased risk of glaucoma due to elevated IOP
what impact do cataracts resulting from pseudoexfoliation have on visual acuity?
no impact on visual acuity
pseudoexfoliation causes enzyme degradation of zonules which leads to?
zonular weakness & phakodenesis
what is the displacement of lens from its normal position?
ectopia lentis
what can cause ectopia lentis?
- trauma
- Marfan syndrome
- pseudoexfoliation syndrome
- high myopia
if a patient with Marfan syndrome develops ectopia lentis, where is the lens usually displaced to? is it bilateral or unilateral?
bilateral, superotemporal
