Iris and Ciliary Body
development of apical to apical NE and PE
due to folding of the optic cup
posterior pigmented epithelium
epithelial cells, larger and more pigmented than anterior pig. epith. basal side faces posterior chamber
radial portion of ciliary muscle
inserts at base of ciliary processes (pars plana) transition layer btwn longitud and circular
circular portion of ciliary muscle
inserts at ciliary body btwen pars plana/plicata (pars plicata)
longitudinal portion of ciliary muscle
inserts into anterior choroid
iris location w/in segments of eye
iris divides anterior and posterior chamber of anterior segment
albinism affect on iris
iris isn't pigmented - lets more light into eye (makes VA worse)
locations of muscles in iris layers
iris sphincter = stroma, in circle at tip of iris iris dilator = stroma and anterior pigmented epith, runs entire lengths of iris PUPIL CONSTRICTION/DILATION
supraciliaris features
melanocytes, fibroblasts, collagen,
anterior non-pigmented epithelia
on posterior side of iris, made of myoepithelial cells (epith cells + muscle cells from iris dilater)
affect of accommodation on other eye structures
opens trabec meshwork, drains aqueous better
melanocytes in anterior border layer/stroma/anter, posterior epith.
present in all layers most in anterior border layer (gives iris its color)
regions of iris
pupillary zone (close to pupil) collarette ciliary zone (close to cil body)
wrinkles in iris
radial and circular types - do due the iris contracting/expanding (creates "slack" in the iris) (on anterior and posterior parts of iris)
iris dilator
radial muscle, goes from anterior pigmented epith into stroma, SYMPATHETICALLY INNERV., extends entire length of iris
clump cells
scavenger cells in iris stroma that eat pigment moleclules
orgin of ALL portions of ciliary muscle (circular, radial, longitud)
sceleral spur
irides
term for many iris's
ciliary body functions
accomm, makes aqueous (and some vitreous) humor
pigmented cells of iris
all contribute to iris color, but ant. border layer most imporant ant. border layer ant/post. pigmented epith.
layers of iris
anterior border layer (anterior side) stroma/iris sphincter muscle (middle) anterior/posterior pigmented epith./iris dilater muscle (posterior side)
blood supply of choroid
anterior choroid: MACI posterior choroid: short posterior cil. artery)
anterior border layer of iris
anterior part of iris STROMA, has meshwork of fibroblasts and melanocytes with melanin (give eye its color) NOT EPITHELIUM!
linking between cells in anterior/posterior pigmented epith.
apical ends of each layer face each other cells joined laterally by tight junctions/desmosomes
thickest anterior border layer
at collarette (where whole iris is thickest)
ciliary body location
behind iris, in front of lens (forms posterior chamber) continuous with choroid posteriorly continuous with iris anteriorly
ciliary stroma
between muscle layer (outer) and epithelial layer (inner) contains MACI, collagen, ciliary processes
pupillary ruff
border between pupil and iris formed by posterior pigmented epithelial that wraps around to anterior side of iris (ant. border layer)
crenations
bumps in the pupillary ruff
venous drainage of iris/CB
chorodal veins, then vortex veins
ciliary body location
choroid becomes ciliary body sclera is on top of both choroid and ciliary body
continuity of cil body/choroid
cil body supraciliaries = contin w/surprachoroidal space cil body stroma = contin w/choroid stroma cil body pigmented epith = continous w/choroid RPE
iris sphincter contraction
circular fibers close like camera, cause more visible pupillary ruff to be seen
iris sphincter
circular muscle, in stroma, PARASYMP. innervated (short cil. nerves) constricts to light and accommodation
ciliary body shape
circular viewed from front triangle viewed from side
trabeculae
collagen fibrils in stroma, seen as radial fibers
MACI flow w/in iris/CB
CB: in stroma, ciliary processes iris: stroma, anterior iris
blood supply of iris/CB
MACI (from long post. cil. artery and anterior ciliary arter) has pericytes to prevent damage from pupil contraction
iris color
darker color due to higher concentration of melanin pigment in melanocytes (most people have same # of melanocytes - so conc. of melanin determines color)
heterochromia
different colored eyes due to asymmetric development or injury
Collarette
divides iris into pupillary zone and ciliary zone
zonules
fibers that attach to lens, come from pars plana AND the ciliary processes of pars plicata
pars plicata
folded part of CB where ciliary processes jutt out ciliary processes are where zonules start ciliary processes/zonules get smaller with age
Major arterior circle of the iris (MACI)
formed by ant. ciliary and long posterior ciliary arteries inside CB stroma (supplies iris and anterior choroid as well)
layers of ciliary body
from anterior to posterior Supraciliaris Ciliary Muscle (longitudinal, radial, circular) Stroma Epithelium (pigmented, then nonpigmented)
type of crypts
fuchs crypts = large, in pupilary zone ciliary crypts = small, in ciliary zone
iris nevus
harmless accumulations of melanocytes in anterior border layer of iris
pars plana
has ciliary bays which go to ora serata (posterior) has striae ciliaris which goes to pars plicata and becomes zonules
pupil
hole in iris, changes in response to light decreases aberrations, increases depth of focus
crypts
holes between the trabeculae strands
continuity of iris/cil body
iris stroma = contin. w/cil body stroma iris anterior pigmented epith = contin. w/outer pigmented epith (PE)of cil body iris posterior pigmented epith (DARK stain) = contin. w/inner non-pigmented epith. (NE) of cil body
uveal tunic of eye
iris, cil body, choroid (all vascular) iris is most anterior part of uveal tunic
eye color of babies
lighter eyes at first, then darker as melanocytes develop
sensory nerves of iris/CB
long ciliary nerves
features of light colored eyes
lower concentration of pigment (melanin) often blue due to light scatter/absorption of shorter wavelengths
ciliary muscle
muscle in the ciliary body that controls accomm
ciliary muscle
muscle that contracts, releasing tension on zonules, allow lens to become rounder (ACCOMODATION) has circular, radial, and longitudinal portions
pupil location
nasal/inferior part of iris
minor arterial circle of iris
near collarette, supplies pupillary iris region, has tight junctions (not complete circle like MACI)
source of ciliary body epithelium
neural ectoderm (like retina)
nonpigmented ciliary epithelium
next to aqueous humor, source of some zonules (the ones coming from pars plana) tight junctions help form blood aqeous barrier
pigmented ciliary epithelium
next to stroma, lots of melanocytes (pigments) lots of gap junctions laterally
ciliary body epithelium
outer pigmented epithelium inner nonpigmented epithelium apical ends of each layer face each other (just like iris epithelia) lots of gap junctions between the two
parasymp/symp of iris/CB
parasymp: ciliary ganglion to short ciliary nerves (stim. ciliary muscle, iris sphincter, choroidal vessels) symp: cervical ganglion to long ciliary nerves (relexes cil muscle, iris dilator, blood vessels)
parts of ciliary body
pars plana = flat part pars plicata = folded part
limbus description
the iris only covers the space behind the cornea, is below/above the sclera
iris thickness
thick at collarette thin at root (peripheral part)
supraciliaris
transition zone between sclera and ciliary body continuous with surprachoroidal space (choroid) - both are under lamina fusca (sclera)
valleys of kuhnt
valleys in between pars plicata mountains
iris stroma
vascular, has collagen, GAGS pigmented cells (melanocytes) and nonpigmented cells (fibroblasts, normal tissue cells)
orra serrata
where dentate processes (teeth like) of retina meets ciliary bays of pars plana
iris root
where iris attaches to CB, seen as the limbus