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Crystalline Lens Disorders
Terms in this set (58)
Weight of lenses by age:
10 yrs: 160mg
Equation for estimating lens weight:
Y=96.8 x X^.21
Y=lens weight in mg
X=age in years
Diameter of the Lens
6.5mm at birth and 9.0mm at age 15 years.
Lens Capsule Facts
Anterior capsule is 5x thicker than posterior capsule.
Anterior capsule is produced by epithelium cells
Posterior Capsule is produced by elongating fiber cells.
composed of polygonal cuboidal cells.
Cell density is higher in females than men.
Fibers (CORTEX) facts:
bulk of lens material.
Tightly bound by interdigitations.
Lens fiber cells consist of 2 major types of cells. (crystalline 90% and cytoskeleton 10%)
Embyronic fiber cells does not form sutures.
Lens fibers grow from one pole to the other, meeting at the sutures.
ERECT Y is anterior and INVERTED Y is posterior.
Facts about the embyronic nucleus
Innermost area of the lens fibers formed in utero.
Prominant in children & progressively harder to see with age.
Contains no sutures or has any other discernable structure.
Fetal Nucleus Facts:
Represents secondary fibers formed in utero.
Prominent in children and progressively harder to see with age.
INNER Stripe of nucleus contains Y sutures.
Approximately 25% of normal eyes show small collections of whitish dots in the region of the anterior Y suture.
Termed "anterior axial embryonal cataract" by Vogt.
Major Types of Age-Related Cataracts
-early or advanced. Brunescent, milky, or nigra
-early or incipient, immature or intuescent, mature, hypermature
-early, moderate, advanced
When the normal lens nucleus hardens and pigments with age.
Known as nuclear sclerois and only when advanced will interfere with VA.
Nuclear Cataract Info:
color progresses from orange to dark brown.
Can result in lenticular myopia or "second sight"
Monocular diplopia may also be seen by patient with small nuclear change acting like a prism.
Most common cataract opacity
2 types of Cortical Cataract (2 others as well)
Cuneiform and Coronary.
Morgagnian and Christmas tree
Early stages of Cortical Cataracts show:
Water clefts: found in anterior cortex
Lamellar Separation: most common location is inferonasal anterior cortex
Cuneiform Opacity: most characteristic sign
Senile Punctate Opacities: "snowflake opacities"
In cortical Cataracts further degeneration can lead to:
Hypermature cataract: which is shrunken, dry, and yellow lens
has possible capsular folding and can appear as a bag of milky fluid.
What is a brown nucleus cataract that sinks to the bottom of a liquefied lens?
It is a Morgagnian cataract. It is a type of Cortical Cataract.
A type of cataract that is formed by cholesterol crystals that are scattered throughout the cortex?
A christmas tree cataract. It is a type of Cortical Cataract.
It looks like tinsel on a christmas tree.
Associated with MYOTONIC dystrophy.
Known as a cupuliform cataract due to it's characteristic mature cup shape.
Occurs at an earlier age than nuclear or cortical.
POSTERIOR subcapsular is much more common than anterior.
Thin layer of granules beneath the capsule which may exhibit as a small granular opacity
Symptoms of subcapsular cataract
Excess glare while driving at night.
Trouble seeing in bright sunlight
Reading difficulty even with a reading lamp.
2 Types of Metabolic Cataracts
1) Galactosemic Cataracts
2) Diabetic Cataract
Cataract caused by an inborn error of metabolism where the infant is unable to metabolize galactose into glycogen. If left untreated will cause death.
Cataract found within days of birth.
Starts in equitorial cortex and spreads anteriorly.
2 types of cataractous changes caused by a disease.
1) Early Senile lens changes
2) True _____ cataract
Snowflake cataract is found in what type of cataract?
Cataract caused by many different wavelengths.
Microwave, infrared, visible, ultraviolet, and ionizing radiation.
"Heat caused" radiation cataract.
glass blowers or furnace folk.
Lens opacity will start in the posterior subcapsular region.
Splitting of the anterior lens capsule results in flaking.
Flakes caused by iris rubbing away deposited amorphous material from anterior lens capsule.
No lens opacity exists.
More common than exfoliation
3 changes following a Traumatic Cataract
1) Vossius Ring
2) Capsular Tear
3) Subcapsular changes (rosette shaped opacity)
--sunflower cataract from copper deposition
--siderosis oculi from rusty foreign bodies
tend to occur axially in the cortex adjacent to the fetal nucleus.
Unilateral or bilateral
Types of ocular defects that may cause congenital cataracts:
Systemic diseases that may cause congenital cataracts
1) Ectodermal dysplasia
2) Werner's Syndrome
3) Congenital Ichthyosis
5) Laurence-Moon-Beidl Syndrome
6) Sjogren's syndrome
7) Rheumatoid arthritis
8) Down's syndrome
Seen as small crystalline opacities near the back of the anterior Y suture.
Cataract is stationary and typically bilateral.
Anterior Axial embryonal cataract
Occurs within 6 months of birth.
Small crystalline opacities near posterior Y suture.
Stationary and bilateral
Opacities are gray or greenish-white lines with knobs projecting
25% of infants.
Minute, nonprogressive opaque dots scattered
Vary in size and color and may be clear when viewed by retroillumination
Located in the outer layers of the adult nucleus and the inner layers of the cortex.
Found in peripheral portion of the lens.
Form corona around periphery of the lens.
Situated at either pole of lens.
Found on capsule, in cortex or both.
2 types of polar cataracts
Anterior and Posterior
Anterior Polar Cataract facts:
Well defined with an occasional extension into cortex.
If peaked forward into anterior chamber, known as PYRIMIDAL cataract.
Embyronic and Fetal nucleus is unaffected.
May progress due to infiltration of calcium salts and cholesterol crystals.
Has been associated with anterior lenticonus.
Posterior Polar Cataract Facts:
Heriditary dominant trait.
Looks much more defined & isn't RIGHT on the capsule
Abnormal peristance of hyaloid artery remnants.
Opacity is usually CONCAVE and fastened to BACK of lens.
2 types of Posterior Polar Cataracts
1) Prenatel Form: clear at birth and remains clear later in life.
2) Clear at birth and opacifies later in life.
Prenatal is the most common and resembles the anterior polar opacity.
Postnatal/progressive produces changes in the posterior chamber.
Also known as a lamellar cataract.
Most common type of development cataract
Zonular Cataract facts:
Bilateral, symmetric and affects males more often than females
Often associated with disorders of Ca metab and avitamintosis D.
V shaped opacities may sometimes be seen extending into cortex; known as riders
2 types of Zonular Cataracts
1) Prenatal or Congenital:
--present @ birth, usually genetic and <5.75mm
--occurs early in infancy due to inherent causes and is >5.75mm.
What are V-shaped opacities that are sometimes seen extending into the cortex known as? what type of cataract are they?
Also known as the diffuse nuclear cataract of Vogt
Central Pulverulent Cataract
Caused by maternal infection with a virus, primary in first trimester
Characteristics of a Rubella Cataract
poorly dilating miotic pupil
salt and pepper retinopathy
Localized deformations in the contour of the anterior and posterior lens surfaces.
If deformity is in shape of a cone, termed __________.
If deformity is in shape of a sphere, termed __________.
Much more common in posterior.
Elevation occurs on the posterior surface of the lens.
Ophtalmoscopy reveals an oil droplet appearance in retroillumination
What type of anomalie is associted with an oil droplet appearance in retroillumination
Rare, bilateral condition where the lens is small in diameter.
Entire lens can be seen through dilated pupil
Characteristics of Microphakia
*eye is highly myopic
*Subluxation is very common due to abnormally long and relaxed zonular attachments
*Pacodonesis or positional changes may occur.
*Inverse angle closure glaucoma is typically associated
*Typically found in WEILL-Marchesani syndrome.
Common congenital anomaly of the lens.
Shows typical inferior indentation or peripheral flattening of the lens.
Corresponding coloboma of the uveal tract.
Ciliary zonules are usually missing
Subluxation or partial dislocation occurs when the zonule is defective.
Lens may be displaced in any direction but remains behind the iris in the patellar fossa.
Characterized by high internal astigmatism
Can be associated with the following systemic dis:
Ectopia lentis et pupillae
Spontaneous Ectopia Lentis may be associated with:
Coloboma of lens and choroid
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