Structure of the Eye Flashcards
What are the three coats of the eye
Fibrous
Vascular
Sensory
What makes up fibroid coat
Cornea
Sclera
All made up of collagen
What is the cornea
Transparent coat over front of eye
Joints to form sclera = opaque
What is cornea layers
Epithelium - Regenerates fast so if scratch will fix in a few days Bowman's basement membrane Stroma - regular collagen Desment Endothelium
What epithelium
Stratified squamous
Non-keratanised
Does cornea have blood vessel
No vessels in storma layer to maintain transparency
Makes corneal graft successful
What parts of cornea heal with or without scar
BM = without Stroma = with
What is behind endothelium
AH
Provides nutrition as no blood vessels
Also nutrition via tear film and sclera
What makes up the vascular coat
Iris
Ciliary body
Choroid
What is choroid
Vascular layer
Where is the iris
Between lens and cornea
Hangs from sclera
What is the aperture in the middle of iris
Pupil
Controls how much light enters
What is the ciliary body
Behind iris
Suspends the lens via ciliary ligaments
What is infront and behind the lens
Infront = AH Behind= VH
What is the sensory coat
Retina
Optic nerve
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What are the layers of the retina an function
Pigment epithelial layer sits on top of choroid
Layer of rod and cones - photoreceptors
Nerve fibre
Inner layer
Retina is responsible for converting light -> neurological signal via photoreceptor cells
What supplies retina
Outer layers = choroid
Inner = central retinal artery - branch of ICA
What are barriers in the eye
Blood aqueous
Blood retinal - prevents capillaries from choroid entering retina
What is anterior segment of eye
Infront of lens
Anterior chamber - in front of iris
Posterior - behind iris where AH is produced
What is posterior segment of the eye
Behind lens
Contains VH
What is AH produced from and how does it flow
Ciliary body
Flows into posterior chamber of anterior segment
Flows through pupil into anterir
Travels through trabeculae meshwork
Drains into Schlemm’s canal at cornea sclera junction
Drains out of eye at angle of anterior chamber into episcleral veins
What is upper and lower eyelid made up of
Skin
Muscle
Connective tissue
Mucous membrane
What does skin contain
Hair follicles
Sebaceous glands which can get blocked
What muscles
LPS - opens
Orbicularis oculi - closes
Meconium gland - oil
What does mucous membrane do
Secretes conjunctiva which liners eyelid and sclera
NOT cornea
What is lacrimal apparatus
Tears come from lacrimal gland
Coat conjunctivae
Drain out of medial eye into lacrimal duct
Join into nasolacrimal duct
What stimulates lacrimal apparatus
Parasympathetic from facial
What is function of tear film
Keep cornea moist
Wash away foreign body
Ab to kill microbes
What are 3 layers
Mucous - conjunctivae
Aquesous - lacrimal gland
Oil - meconium gland
Importance of lens
Avascular so transparent
Can’t shed old fibres so at risk of opacification
