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
What is the role of the iris?
Controls diameter of the pupil so controls amount of light rays entering the eye
What is the role of the choroid?
Supplies blood to outer layers of retina
What os the role of the retina?
Light sensitive rods and cones which enables sight
What is a lens opacification commonly known as?
Cataract
What is the role of the aqueous humour?
Maintains intraocular pressure
What is the role of the vitreous humour?
Cushions the retina
What is the role of the trabecular meshwork?
Filters aqueous humour through it
Where does the lacrimal gland receive innervation from?
Parasympathetic from facial nerve
Where does the duct of the lacrimal gland open?
Conjunctival sac
What is the role of a tear film?
Keeps cornea moist
Washes away any foreign bodies
Contains antibodies and lysozymes to kill microbes
Provides smooth surface for refraction
