Anatomy and Embryology of the Eye Flashcards
Where is the eye derived from embyrologically?
Neural tube
How are the optic vesicles formed?
Grow out from diencephalic part of neural tube
Reach surface ectoderm and cells thicken to form lens placode
Lens placode starts to push inwards, optic vesicle to form an optic cup
How many layers does the optic cup process?
2 layers
What is the choroid fissure?
A hole on the inferior wall of the optic cup through which blood vessels pass
What happens to the choroid fissure?
Disappears, can persist to form a gap called a coloboma
What does the surface ectoderm go on to form?
Eyelids
Conjunctiva
Corneal epithelium
What does the mesenchyme form?
Choroid
Stroma of cornea
Sclera
Extraocular muscles
What is a retinal detachment?
Liquified vitreous enters through holes in the peripheral retina into space between outer and inner layers of optic cup
What is the function of orbital fat?
Cushions globe
Important for support
What type of epithelium is present on the cornea?
Stratified squamous non-keratinised
How is the transparency of the cornea maintained?
Regular arrangement of collagen in stroma
No blood vessels
Endothelium pump keeps aqueous humour out
What role does avascularity play in corneal transplants?
Lesser chance of foreign antigens from graft being recognised by recipient so less chance of rejection
What is the role of the cornea?
Allow light rays to enter eyeball
What is the role of the sclera?
Gives attachment to muscles moving the eyeball
What is the role of the ciliary body?
Suspends the lens
Produces aqueous humour