IRIS Flashcards
1
Q
UVEA STRUCTURES
A
- iris
- ciliary body
- choroid
2
Q
UVEA
A
- vascular layer of eye
- between sclera + retina
- made up of BV’s in a loose network of connective tissue + pigment cells
- BV’s provide circulation to eye
- pigment prevents unwanted light entering eye + reduces light reflections
3
Q
IRIS STRUCTURE
A
thin contractile pigmented diaphragm with central aperture (pupil)
4
Q
IRIS FUNCTIONS
A
- controls amount of light reaching retina
- depth of focus
- reduces aberrations
- forms division between anterior + posterior chambers
- suspended in aqueous humour between cornea + lens
- attached to ciliary body at iris root
5
Q
PUPIL
A
- not located centrally
- displaced slightly down + in
- width of the ciliary region alters the most, the pupillary zone remains almost constant
6
Q
MYDRIASIS
A
dilation of pupil
7
Q
MIOSIS
A
constriction of pupil
8
Q
IRIS COLOUR
A
- depends on pigmentation of ant. surface
- more pigmentation -> browner iris + more underlying structure is hidden
- little/ no pigment -> blue, as scattering of light in stroma
9
Q
HETEROCHROMIA
A
large variations between colours of eye
10
Q
ANISOCORIA
A
unequal size of pupils
11
Q
IRIS LAYERS
A
- anterior border layer
- stroma
- epithelium
12
Q
ANTERIOR BORDER LAYER (outer)
A
- dense covering
- melanocytes (contain granules of pigment melanin)
- fibroblasts + collagen fibres
- no epithelium
13
Q
CRYPTS
A
allow aqueous humour to access tissues of the iris
14
Q
STROMA
A
- collagenous
- connective tissue containing fibroblasts + pigment cells in a mucopolysaccharide matrix
- iris blood vessels + sphincter muscle contained here
15
Q
SPHINCTER PUPILLAE MUSCLE
A
- band of smooth muscle
- runs parallel to pupil margin
- in extreme miosis the whole muscle can be reduced to 15%
