14. Eye Development

Question 1

Answer 1

aniridia

• PAX6 gene mutation
• lack of iris tissue or complete absence of the iris
• defect results from: “arrested development of the rim of optic cup”
• associated with: glaucoma, cataracts, and other eye abnormalities

Question 2

Answer 2

congenital cataracts

• opaque lens (gray/white)
• usually bilateral
• fairly common and may result from the following:
  
  • genetics, Rubella virus [lens vulnerable b/w 4-7 weeks], toxoplasmosis, congenital syphilis, Down syndrome (trisomy 21), galactosemia (galactose from mik accumulate in blood and tissues)

Question 3

Answer 3

congenital glaucoma

• increased IOP due to abnormal development of the canal of Schlemm, iridocorneal filtration angle, or mechniasm of aqueous humor drainage (scleral venous sinus)
• causes: genetics (mutations in CYP1B1 gene) Rubella infection

Question 4

edema due to increased intracranial pressure

reflected into subarachnoid space, surrounding optic nerve (CNII)

Answer 4

papilledema

Question 5

What causes this?

Answer 5

persistence of the distal part of the hyaloid artery

*eye may be microphthalmic

Question 6

Answer 6

colomboma iridis

• cleft in the iris caused by failure of choroid/optic fissure to close in week 7 of development
• may extend into ciliary body, retina, choroid, or optic nerve
• causes: environmental factor, autosomal dominant

Question 7

eye symptoms for congenital infections: Rubella virus

Answer 7

cataracts, microphthalmos, glauoma, pigmented retinopathy

Question 8

eye symptoms for congenital infections: Toxoplasma gondii

Answer 8

microphthalmia

Question 9

eye symptoms for congenital infections: Venezuelan equine encephalitis virus

Answer 9

microphthalmia

Question 10

eye symptoms for congenital infections: Varicella virus

Answer 10

cataracts, microphthalmia, optic atrophy

Question 11

derived from mesenchyme/NCC

Answer 11

• sclera
• cornea (stroma)
• choroid
• iris (stroma)
• ciliary body (stroma/ciliary muscle)

Question 12

derived from neural ectoderm

Answer 12

• retina (optic cup)
• iris (smooth muscle, pigmented epithelium)
• ciliary body (epithelium)

Question 13

derived from surface ectoderm

Answer 13

• lens
• cornea (epithelium)