Lecture 14: Eye Development

Question 1

When is the critical period for fetal eye development?

Answer 1

Weeks 4-8

Question 2

What embryonic layers give rise to the eye?

Answer 2

Neuroectoderm

Surface ectoderm

Mesoderm/Neural Crest

Question 3

What part of the brain does the eye originate from?

Answer 3

Diencephalon

Question 4

What do the rims of the optic cup give rise to?

Answer 4

Iris and ciliary body

Question 5

What muscles are the only muscles in the body to arise from neuroectoderm?

Answer 5

Dilator and Constrictor pupillae muscles

Question 6

What embryonic layer gives rise to the stroma of the iris?

Answer 6

Neural Crest

Question 7

What embryonic layer gives rise to the epithelium of the iris and the ciliary body?

Answer 7

Neuroectoderm

Question 8

What embryonic layer gives rise to the smooth muscle cells of the ciliary body?

Answer 8

Mesoderm

Question 9

What congenital disorders can predispose a patient to having separation of the pigmented and neural retina?

Answer 9

Down’s syndrome

Marfan’s syndrome

Question 10

Redevelopment of the intraretinal space comes from separation of what layers?

Answer 10

Neural retina (inner layer) and pigmented retina (outer layer)

Question 11

What is aniridia?

What can cause it?

Answer 11

Lack of iris tissue

• Defects in the Pax6 gene
• Glaucoma, cataracts, other eye abnormalities

Question 12

Arrested development of what optic structure during the 8th week can result in aniridia?

Answer 12

Rim of optic cup

Question 13

What embryonic layer gives rise to the lens of the eye?

Answer 13

Surface ectoderm

Question 14

What structures of the lens are responsible for its transparent nature?

Answer 14

Primary lens fibers - columnar epithelium with dissociated nuclei

Question 15

What optic structure do cataracts affect?

Answer 15

Lens

Question 16

Maternal rubella infection between 4-7 weeks gestation can have what effect on fetal eye development?

Answer 16

Congenital cataracts (vulnerable lens development)

Congenital glaucoma

Also can be caused by genetics, rubella virus, radiation, and enzyme deficiency

Question 17

A 3 week old patient presents with congenital cataracts. He is being breastfed. What is the most likely diagnosis?

Answer 17

Congenital Galactosemia

-Accumulation of galactose from milk because of enzyme deficiency

Question 18

What layer of meninges is the sclera continuous with?

Answer 18

Dura

Question 19

What layers of meninges is the choroid continuous with?

Answer 19

Pia and arachnoid

Question 20

What optic structure does the pupillary membrane arise from?

Answer 20

Sclera

Question 21

When happens to the pupillary membrane?

Answer 21

Degenerates at Week 26

Question 22

What secretes the aqueous humor in the posterior chamber?

Answer 22

Ciliary Epithelium

Question 23

What is the embryonic origin of primary vitreous humor?

Answer 23

Choroid (mesenchyme/NCC)

Question 24

What makes the aqueous humor?

Answer 24

Ciliary Body

Question 25

Abnormal neural crest migration to form the scleral venous sinus results in an inability to drain what ocular fluid?

Answer 25

Aqueous humor

Question 26

Defects in what gene can cause congenital glaucoma?

Answer 26

CYP1B1

Question 27

Elevated intraocular pressure can place patients at risk for what disorder?

Answer 27

Congenital Glaucoma

Question 28

What is the embryonic origin of the extra-ocular muscles?

Answer 28

Prechordal mesenchyme

Question 29

What embryonic artery gives rise to the Central Retinal Artery?

Answer 29

Proximal portion of the Hyaloid Artery

Question 30

What does the Hyaloid A. supply during fetal eye development?

Answer 30

Inner layer of optic cup Lens vesicle Optic cup mesenchyme

Question 31

What embryonic layer gives rise to the blood vessels of the eye?

Answer 31

Mesoderm

Question 32

What embryonic arteries do the ciliary arteries give rise to?

Answer 32

Choroidal vessels

Question 33

When do the choroidal vessels develop during fetal eye development?

Answer 33

15th week

Question 34

What nourishes the eye when the choroidal vessels degenerate?

Answer 34

Aqueous humor

Question 35

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?

Answer 35

Persistence of the distal portion of the Hyaloid A.

Question 36

What is the optic stalk's relationship to the optic nerve?

Answer 36

Provides the template and pathway for optic nerve DOES NOT BECOME OPTIC NERVE

Question 37

What becomes the optic nerve?

Answer 37

Neurons of Ganglion Cells

Question 38

What space will papilledema collect in? Why does this happen?

Answer 38

Subarachnoid space of the meninges covering the optic vessels Increased intracranial pressure slows venous return from retina

Question 39

A patient presents with a key-lock appearing pupil. What is their most likely diagnosis?

Answer 39

Coloboma

Question 40

What is the embryological cause of coloboma?

Answer 40

Optic fissure fails to close completely, leaving a gap in the iris

Question 41

What is the genetic inheritance of coloboma?

Answer 41

Autosomal dominant

Question 42

What does the neuroectoderm give rise to in the eye?

Answer 42

Forebrain * Retina * Neural retina (inner layer) * Pigmented retina (outer layer) * Iris * Pupillae Muscles * Epithelium * Epithelium Ciliary Body * Optic Nerve

Question 43

What does the Surface Ectoderm give rise to?

Answer 43

Head * Lens of Eye * Corneal Epithelium

Question 44

What does the mesenchyme give rise to in the eye?

Answer 44

Between surface and neuroectoderm * Sclera * Stroma of Cornea * Choroid (mostly NCC) * Stroma of Iris * Stroma of Ciliary Muscle