Eye Development Flashcards
What part of the developing brain do structures of the eyes come from? What else comes from this
Prosencephalon
Things with thalmus in name
What does the optic vesicle become during development? When does this happen? What is it attached to?
Optic cup
Week 4
optic stalk
What’s contained in the optic fissure?
vasculature
What is the optic sulcus?
Groove only seen from inside of developing eye
What does the retina arise from? What are its 2 layers?
Neuroectoderm
Neural retina (inner) Pigmented retina (outer)
What do the structures of the iris arise from? Where do you find them during development?
Epithelium= neuroectoderm
Stroma= mesenchyme (mesoderm AND NCC)
SMC aka pupillae muscles= neurectoderm (only muscles that come from neurectoderm)
Tip of optic cup
What do the structures of the ciliary body arise from? Where do you find them during development?
Epithelium= neuroectoderm SMC= ciliary muscles, from mesoderm and NCC aka mesenchyme
What is the critical period for eye development?
Week 4-8
Can have defects up to birth though
What causes retinal detachment?
The inner and outer layers of the retinal cup fail to fuse
- common in people with marfan’s or downs
- can also be caused by trauma to eye
What is aniridia? Embryologically how is this caused? What gene mutation is it associated with?
Lack of iris tissue or complete absence of iris
Arrest of development at rim of optic cup during 8th week
Pax6 gene
How does the lens develop? What layer does it come from?
Induced by optic cup
Lens placode grows out touching surface ectoderm resulting in new genetic signaling and thickening of surface ectoderm –> invaginate and become lens pit –> round up and become lens vesicle
Surface ectoderm
What fibers during development are important in ensuring the lens is clear?
anterior lens epithelium
primary lens fibers
secondary lens fibers
Where do the parts of the cornea arise from?
Epithelium= surface ectoderm
Stroma= mesenchyme (includes NCC)
What can cause congenital cataracts?
Genetics
Rubella virus during weeks 4-7
Radiation
Enzyme deficiency –> congenital glactosemia, appears 2-3 weeks after birth when galactose from milk accumulates
Lens is opaque and grayish white, ONLY LENS OPAQUE (different than glaucoma)
What does the sclera develop from? What are its parts?
Mesenchyme/NCC
Outer layer continuous with dura matter
Fibrous
stroma of cornea
What does the choroid develop from? What are its parts?
Heavily NCC
Inner layer continous of pia and arachnoid matter
Vascularized
What is the pupillary membrane? When does it normally disintegrate?
extension of the sclera, covers the lens as it is developing
during months 6-8
What is the pathway of aqueous humor?
Secreted by ciliary epithelium (neuroectoderm) –> posterior chamber –> pupil –> ant chamber –> reabsorbed by scleral venous sinus (mesenchyme)
What is virteous humor made by?
The choroid
Gel like substance in eye when cut open
What does congenital glaucoma result from embryologically? Pathologically?
Abnormal development of drainage mechanism of aqueous humor aka sclera venous sinus –> elevated intraocular pressure
Genetics, CYP1B1 mutation
Rubella
Where do the extra-cular muscles arise from? are they arch structures?
Prechordal plate mesenchyme
NOOO
What does the hyaloid artery arise from? What does it supply? What does it differentiate into? What does it supply?
Mesenchyme (branch of the ophthalmic a.)
Inner layer of optic cup, lens vesicle, mesenchyme in optic cup
Distal “webbing” disintegrates and becomes central artery surrounded by optic stalk supplying only the retina
What does the choroidal vessel develop from? When does this happen?
Mesenchyme, specifically anterior and posterior ciliary arteries
15th week
What happens if there is persistence of the hyaloid a. distally?
See floating worm in eye
Normally associated with cases of microphthalmic aka small eye condition
Little/no defects
What does the optic nerve come from? What are its layers?
Neuroectoderm
Pigments= rods and cones, ganglion cells
Fibrous layer= axons forming optic nerve
How does the optic nerve form?
Inner layer of optic stalk with axons and ganglion
- axons grow through the inner part of the stalk forming nerve and cavity obliterated
- hyaloid a incorporated into substance of optic n.
finally in 7th week artery covered by all 3 meningeal layers
What is papilledema?
Increased intracranial pressure –> slow venous return from retina –> fluid accumulation of the optic disc –> edema because vessels covered by meninges and lie in extension of subarachnoid space
OPTIC DISC BULGE
What is colobma? Embryologically how does this arise?
Key hole pupil –> in bright light cant constrict at that point so can cause damage to retina
Failure of optic fissure to close
- can be caused by environmental factors or autosomal dominant mutation
What defects can the rubella virus have on the eye?
Cataracts
Microphthalmos
Glaucoma
Pigmented Retinopathy
What defects can taxoplasam gondi (intracellular parasite fro uncooked meat, soil, infected animals)?
Micropthalamia
What defects can venezuelan equine encephalitis virus have on the eye?
micropthalmia
What defects can varicella (chicken pox) have on the eye?
cataracts
microphthalmia
optic atrophy
