lens and cats Flashcards
mittendorf dot is from what embryonic structure
hyaloid artery
epicapsular star is from what embryonic structure?
tunica vasculosa lentis
Peter’s anomaly via what mechanism?
anterior segment dysgenesis/ failure of lens vesicle and surface ectoderm (cornea)at around 33 weeks
Pete’s anomaly is associate with what gene defects
PAX6, PITX2, FOXC1
Peter’s anomaly is associated with what defects?
- central/paracentral leukoma (corneal opacity)
- thinning/absent endothelium/descemet’s
- Iris sticks to cornea (type 1); iris sticks to lens (type 2)
- anterior cortical cataracts
- microspherophakia
- anteriorly displaced lens
What is microspherophakia? It’s associated with what condition(s)?
whole equator of lens can be seen when fully dilated… leading to high refractive power thus high myopia
- primarily Weill-Marchesani syndrome
- Peter’s anomaly
- Alport’s syndrome
- Lowe’s syndrome
- Marfan’s syndrome
what is a feared complication of microspherophakia? what can exacerbate this? what can treat this complication?
Acute angle closure glaucoma.
- Exacerbated by miotics
- Treat with cycloplegics–>to pull the lens posteriorly
Congenital aphakia:
what is primary aphakia vs secondary aphakia?
Primary aphakia is when lens placode does not form
Secondary aphakia is when the forming lens is absorbed.
What is aniridia? unilat or bilat?
no iris (partial or whole) almost always bilateral
nonhereditary aniridia… what two conditions do you have to worry about?
what’s a common complication of aniridia?
Wilm’s tumor
WAGR complex– wilm’s, aniridia, genitourinary, mental Retardation
-early cataract formation
Definition of congenital (aka infantile) cataracts
seen at birth or within 1 year of birth
Most common type of congenital cataract? what are its features? usual pattern of inheritance?
also called zonular.
It has layer of opacification surrounding the nucleus and itself is surrounded by clear cortex.
May have adjacent horseshoe shaped opacity called “riders”
-autosomal dominant
Types of congenital cataracts
lamellar, polar, sutural, cerulean, membranous, coronary, nuclear, capsular, complete
features of anterior polar cataracts. Mode of inheritance. Clinical significance?
-Anterior polar–aka subcapsule and involving cortex.
-autosomal dominant
-usually bilateral, non progressive, no impairment of vision
but could cause anisometropia. sometimes seen with anterior lenticonus, persistent pupillary membranes, microophthalmia
sutural cataracts are also called what?
Stellate cataracts
features of posterior polar cataracts?
Mode of inheritance.
Features of hereditary vs sporadic.
Usually larger and more clinically significant than anterior polar cataracts.
- Associated with capsular fragility
- Autosomal dominant. Inherited is usually bilateral versus sporadic can be unilateral and associated with persistent tunica vasculosa lentil and lenticonus
Sutural cataracts.
Features?
Mode of inheritance?
Clinical relevance?
opacities along the fetal suture lines.
Autosomal dominant
Usually not of clinical significance
Features of coronary cataracts?
a club shaped cortical opacity usually at the periphery and can’t be seen unless dilated.
-autosomal dominant inheritance
Cerulean cataracts are also called what? Features of cerulean cataracts?
Blue dot cataracts.
small bluish opacities on the lens CORTEX.
usually not clinically significant and non progressive
Medical indications for cataract surgery. (4)
- obscured view to back of eye in order to assess for other conditions such as AMD, DR…etc
- dislocated lens
- phacolytic glaucoma, pharmacomorphic glaucoma (due to intumescent lens –rapid thickened–
- phacoantigenic uveitis
Most common indication for cataract surgery?
elective desire to improve vision
What is the key clinical association with congenital nuclear cataracts?
What is a feared complications?
congenital nuclear cataracts tend to be associated with micro-ophthalmic eyes.
Increased risk of aphasic glaucoma (which is the most common long term complication s/p congenital CE)
Capsular cataracts.
features?
clinical significance
involves the anterior lens capsule and epithelium. DOES NOT involve the cortex. Protrudes in to the AC?
Generally not clinically significant
What is it called when the entire lens is opacified in a <1 year old?
Complete cataract
What is a membranous congenital cataract? Clinical significance?
lens protein resorption from lens (often s/p trauma) allowing anterior and posterior capsules to fuse.
Usually clinically very significant.
Why is CE in congenital rubella infection patients associated with more inflammation?
Rubella virus lives within the lens fibers and live virus can persist 3 years s/p birth. disruption of fibers cause viral release.
What kind of cataracts are associated with congenital rubella infection?
Dense nuclear cataracts Complete cataract (cortex sometimes liquified)
Congenital Rubella syndrome:
-associations? (5)
- microophthalmia
- Corneal clouding (transient or permanent)
- cataracts (nuclear or complete)
- glaucoma
- diffuse pigmentary retinopathy
(of note: usually glaucoma and cataracts are not simultaneously in the same eye)
what is ectopia lentis
displacement of lens–can be congenital, developmental, or acquired.
what is the difference between lens subluxation vs dislocation (luxation)
Subluxation implies displaced but still in the pupillary space.
Dislocation implies complete displacement from the pupillary space indicating disruption of zonules.
Symptoms of lens subluxation?
decreased VA, monocular diplopia, high astigmatism, iridodonesis.
what is the most common cause of lens dislocation?
trauma
What are non traumatic causes of dislocation?
Congenital glaucoma
Homocysteinuria
Aniridia
Marfan’s
–less common causes: weill-marchensani, ehlers dans, hyperlysinemia, sulfite oxidase deficiency, simple ectopic lentil as inherited.
Marfan syndrome
- mode of inheritance? genetic aberrance?
- ocular manifestation?
- Complications to be on the look out for due to ocular findings?
- Cardiovascular associations?
- musculoskeletal associations
- autosomal dominant, mutation of fibrillar gene on Chr 15.
- ectopia lentis (usually supratemprally) bilateral symmetric with elongated zones. axial myopia
- increase risk of RD due to myopia; and angle closure glaucoma and amblyopia, poor accommodation due to lens subluxation/dislocation.
- MVP, aortic root dilatation
- long limbs, arachnodactyly
CE in Marfan’s syndrome is associated with what complications? (2)
vitreous loss, RD
Homocystinuria
- Mode of inheritance?
- what is the disease?
- Systemic manifestations?
- Ocular manifestations?
- autosomal recessive
- elevated homocysteine and methionine.
- seizures, osteoporosis, cognitive impairment, tall, light colored hair, VTEs
- bilat symmetric lens dislocations (30% at birth; 80+% are affected by 15) usually infranasal (zonules are high in cysteine)
How to treat homocystinuria?
low methionine diet,
supplement cysteine diet and vitamin B6
Clinical features of hyperlysinemia?
ectopia lentis, muscular hypotony, cognitive impairment
What is the gene identified to be associated with cortical cataracts?
EPHA2–age related cortical cataracts
What is the number one risk factor for developing cataracts (age related non syndromic)
genes!
What are the features of ectopia lentis et papillae?
other ocular associations?
asymmetric eccentric dislocation of lens in the opposite direction of abnormal pupil (which is eccentric and irregular)… hard to dilate.
-Associated with enlarged corneal diameter, atrophic pupils with transillumination defects, cataract, RD, axial myopia,
persistent fetal vasculature (PFV) is also known as what?
PHPV (persistent hyperplastic primary vitreous)
three types of age related cats
nuclear, cortical, and sub capsular
what does intumescence mean?
swollen and enlarged cataract–watch out for angle closure
What are Wedl Cells?
The abnormally swollen/enlarged cells in PSC when epithelial lens cells migrate from equator in to the visual axis.
what are the ocular side effects of corticosteroids?
elevated IOP, PSCs
Does slow release intraocular steroids (subconj and intravitreal) lower risk of IOP elevation and PSCs?
no
ocular manifestations of amiodarone? (2)
verticillata, optic neuropathy
what class of drug is chlorpromazine and thioridazine? what kind of visual side effect does it cause?
these are phenothiazines (psychotropic meds).
can cause pigment deposition to anterior lens… usually not visually significant.
What is a ocular complication of anticholinesterase medications? what are examples of this class of med?
It causes cataracts (starting with vacuoles then cortical and nuclear opacification)
-pilocarpine and thiophate iodide (for echo)
cataract incidence with statin is increased with concurrent use of what medication?
erythromycin
what ocular side effect does Tamoxifen has?
crystalline maculopathy (NOT cats)
what is a vossius ring? what does it signify?
imprint of pigment in the shape of the pupil to the anterior lens. Indicates prior blunt trauma
What is a rosette cataract?
Rose like cataract s/p blunt trauma involving visual axis and posterior capsule. Mild ones can resolve.
What surgical procedure is associated with nuclear cataracts? What are other procedures associated with cats?
trans pars plana vitrectomy
intravitreous injections, trabeculectomy, penetrating keratoplasty
Which population is more susceptible to lens damage and delayed cats from ionizing radiation?
young patients as they have more actively replicating lens cells.
siderosis bulbi is caused by what?
iron containing FB
Siderosis bulbi features? long term implications?
yellow colored iron depositions in the iris, trabecular meshwork, lens epithelium/cortical fibers… can lead to cortical cataracts and retinal dysfunction long term.
What is a sunflower cataract?
Chalcosis: aka copper deposition to various basement membranes via intraocular FB.
What is chalcosis
intraocular FB, deposition of copper to descent’s, anterior lens capsule. Copper intraocular FB can also cause severe inflammatory reaction and necrosis
characteristics of electrical injury induced cataracts?
likely when pt’s head is involved in the electrical current.
First anterior vacuoles are seen in the lens. then linear opacities in anterior sub capsule cortex.
what’s more likely to involve intraocular abnormalities? acid injuries or alkali injuries?
alkali
what are likely injuries from alkali chemical injuries?
injuries to cornea, conj, iris, and lens leading to cats.
what are two causes of verticillate?
Amiodarone, fabry’s
What is a snowflake cataract? what population is it associated with?
- Associated with diabetics–generally type I, young, and uncontrolled.
- It’s a axial rapidly developing sub capsular and cortical cataract that has the appearance of a snow flake.
what are the three lens abnormalities associated with an “oil droplet” appearance”? which two are similar?
nuclear sclerosis and galactosemia –similar
posterior lenticonus is different as it casts an oil droplet appearance on the red reflex.
What are the three enzyme deficiencies responsible for galactosemia?
galactose-1-phosphate uritidyl transferase (Gal-1-PUT) is classic galactosemia
galactokinase, and UDP-galactose 4 epimerase
how do you confirm classic galactosemia?
presence of galactose in the urine
What are the systemic and ocular signs and symptoms of galactosemia?
malnutrition, hepatomegaly, jaundice, cataract development (NSC and cortical from deep out)
What is the treatment for galactosemia?
elimination of milk from diet
what do hypocalcemia (tetanic) cataracts look like? laterality? can be caused by what?
punctate iridescent opacities in the cortical layers separated by zones of clear lens. bilateral usually
-can be associated with parathyroid/thyroid surgery
high copper related ocular abnormalities? (Wilson’s disease)
Kaiser Fleischer ring (descemet’s) and sun flower cataracts (usually not visually significant.
where is kaiser fleischer ring located
descemet’s membrane of the cornea.
polychromatic iridescent crystals of the lens are associated with what disorder? what are these crystals?what other ocular abnormalities do these patients have?
myotonic dystrophy; cholesterol crystals; ptosis, facial musculature weakness, progressive cataracts