EYE Flashcards
function of vitreous chmaber
- nourishes eye
- refracts light
- maintains shape of eye
function of aqueous
nourishes the eye through diffusion of nutrients and o2
- refracts light and maintains shape of eye
what forms neural retina
optic vesicle to optic cup
what forms lens
lens placode to lens pit
layers of the sclera
- fibrous
- vascular
- retinal
function of fibrous layer in the sclera
provides shape and support
what is the fibrous layer of sclera made of
sclera and cornea
what does the bowmans membrane support
corneal epithelium
list the 6 layers of the cornea
- basement membrane
- bowmans membrane
- collagen fibrils
- ketaocytes
- duas layer
- descemets membrane
descemets membrane
supports endothelium
what does the vascular layer of uvea consists of
choroid
iris
ciliary body
function of irisi
pigmentation defines eye colour and controls the size of pupils to regulate levels of light
what is pupil size (iris) controlled by
circular and radial muscle fibres
what is ciliary muscles made up of
equatorial circular fibres
- reticular radial fibres
- meridinal longitudinal fibres
function of lens
transmits and focusses light onto the retina
list the two. layers of the retina
- neural layer
- pigmented layer
what does the neural layer of the retina have
photoreceptors (light detecting cells)
what does the pigmented layer of the retina have
attaches to coroid and supports neural cells, prevents internal refraction of light
how is the retina viewed
fundoscopy
what can we see in the retina
optic disc
macula lutea
fovea centralis
light entering the eye is focused by
cornea and the lens tohit the photosensitive rods and cones of the retina
what is cataracts
loss of lens transparency
loss of light focusing ability
focus 2/3 cornea, 1/3 lens
what causes the loss of lens transparency
change to lens cell organisation
altered lens cell morphology
diabetes
age
family history etc
3 types of cataracts
- nuclear sclerotic
- cortical spoking
- subscapular > anteiror or posterior
what is nuclear sclerotic cataract
most common age related one
impacts the centre of the lens > hardening and discolouration
BROWN NUCLEUS
how does cortical spoking cataract start
white streaks on rim of lens
swelling of cortex
what does cortical spoking cataract causes
light scattering glare and halo effect
what is posterior scapular cataract more common in
diabetic peoope and steroid users
treatments for all types of cataract
- laser assisted
- phacoemulsificaton
- insertion of intraocular lens
what is the neural layer of the eye
retinal
how many layers in the neural retinal layer of the eye
2
neural
pigmented
list the structures of the uvea
iris
choroid
ciliary body
function of ciliary body
accomodation
what is needed for accomodation
ciliary body and zonule fibres
explain accomodation with its relationship to ciliary body and zonule fibres
ciliary body contracts > causing the zonule tensions to relax > lens becomes rounded
tension by zonule fibres extending from ciliary body to lens > lens become flatter
what is the pupil size of the iris controlled by
circular and radial muscle fibres
what does ciliary body produce
aqueous humour by pigmented epithelia
