Lecture 14: Eye Development Flashcards
When is the critical period for fetal eye development?
Weeks 4-8
What embryonic layers give rise to the eye?
Neuroectoderm
Surface ectoderm
Mesoderm/Neural Crest
What part of the brain does the eye originate from?
Diencephalon
What do the rims of the optic cup give rise to?
Iris and ciliary body
What muscles are the only muscles in the body to arise from neuroectoderm?
Dilator and Constrictor pupillae muscles
What embryonic layer gives rise to the stroma of the iris?
Neural Crest
What embryonic layer gives rise to the epithelium of the iris and the ciliary body?
Neuroectoderm
What embryonic layer gives rise to the smooth muscle cells of the ciliary body?
Mesoderm
What congenital disorders can predispose a patient to having separation of the pigmented and neural retina?
Down’s syndrome
Marfan’s syndrome
Redevelopment of the intraretinal space comes from separation of what layers?
Neural retina (inner layer) and pigmented retina (outer layer)
What is aniridia?
What can cause it?
Lack of iris tissue
- Defects in the Pax6 gene
- Glaucoma, cataracts, other eye abnormalities
Arrested development of what optic structure during the 8th week can result in aniridia?
Rim of optic cup
What embryonic layer gives rise to the lens of the eye?
Surface ectoderm
What structures of the lens are responsible for its transparent nature?
Primary lens fibers - columnar epithelium with dissociated nuclei
What optic structure do cataracts affect?
Lens
Maternal rubella infection between 4-7 weeks gestation can have what effect on fetal eye development?
Congenital cataracts (vulnerable lens development)
Congenital glaucoma
Also can be caused by genetics, rubella virus, radiation, and enzyme deficiency
A 3 week old patient presents with congenital cataracts. He is being breastfed. What is the most likely diagnosis?
Congenital Galactosemia
-Accumulation of galactose from milk because of enzyme deficiency
What layer of meninges is the sclera continuous with?
Dura
What layers of meninges is the choroid continuous with?
Pia and arachnoid
What optic structure does the pupillary membrane arise from?
Sclera
When happens to the pupillary membrane?
Degenerates at Week 26
What secretes the aqueous humor in the posterior chamber?
Ciliary Epithelium
What is the embryonic origin of primary vitreous humor?
Choroid (mesenchyme/NCC)
What makes the aqueous humor?
Ciliary Body
Abnormal neural crest migration to form the scleral venous sinus results in an inability to drain what ocular fluid?
Aqueous humor
Defects in what gene can cause congenital glaucoma?
CYP1B1
Elevated intraocular pressure can place patients at risk for what disorder?
Congenital Glaucoma
What is the embryonic origin of the extra-ocular muscles?
Prechordal mesenchyme
What embryonic artery gives rise to the Central Retinal Artery?
Proximal portion of the Hyaloid Artery
What does the Hyaloid A. supply during fetal eye development?
Inner layer of optic cup
Lens vesicle
Optic cup mesenchyme
What embryonic layer gives rise to the blood vessels of the eye?
Mesoderm
What embryonic arteries do the ciliary arteries give rise to?
Choroidal vessels
When do the choroidal vessels develop during fetal eye development?
15th week
What nourishes the eye when the choroidal vessels degenerate?
Aqueous humor
A patient presents to the ophthalmologist for a checkup. On examination, the patient’s left eye is smaller than usual and has a worm-like structure on the inside?
What is the most likely cause of this?
Persistence of the distal portion of the Hyaloid A.
What is the optic stalk’s relationship to the optic nerve?
Provides the template and pathway for optic nerve
DOES NOT BECOME OPTIC NERVE
What becomes the optic nerve?
Neurons of Ganglion Cells
What space will papilledema collect in?
Why does this happen?
Subarachnoid space of the meninges covering the optic vessels
Increased intracranial pressure slows venous return from retina
A patient presents with a key-lock appearing pupil. What is their most likely diagnosis?
Coloboma
What is the embryological cause of coloboma?
Optic fissure fails to close completely, leaving a gap in the iris
What is the genetic inheritance of coloboma?
Autosomal dominant
What does the neuroectoderm give rise to in the eye?
Forebrain
- Retina
- Neural retina (inner layer)
- Pigmented retina (outer layer)
- Iris
- Pupillae Muscles
- Epithelium
- Epithelium Ciliary Body
- Optic Nerve
What does the Surface Ectoderm give rise to?
Head
- Lens of Eye
- Corneal Epithelium
What does the mesenchyme give rise to in the eye?
Between surface and neuroectoderm
- Sclera
- Stroma of Cornea
- Choroid (mostly NCC)
- Stroma of Iris
- Stroma of Ciliary Muscle
