Oc. Phys Iris and Ciliary Body

Anterior Border layer

neural crest

anterior leaf (stroma) of the iris

3rd wave neural crest mesenchyme

posterior leaf (stroma) of iris

4th wave neural crest mesenchyme

anterior and posterior epithelium

neural ectoderm

dialtor and sphincter

neural ectoderm

Anterior leaf is formed from

3rd wave of neural crest mesenchyme migrated in from tip of optic cup

the 3rd wave migrates

in front of the future pupil to form a vascular membranes called the iridopupillaty membranse or ATVL that will nourish the developing anterior lens

the ATVL will

atrophy to form the pupilary opening

Anterior leaf differentiates

into the anterior stroma in the ciliary portion of the iris.

will eventually atrophy to the collarette

4th wave of neural crest mesenchyme

migrates in underneath the 3rd wave to form the posterior region on the iris stroma

4th wave of neural crest differentiates into

the posterior stroma in the ciliary portion of the iris

all of the stroma in the pupillary region becuse the 3rd eave atropied bacl to the collarete.

the annular system

is replaced by branches from the major arterial circle

major arterial circle formation

2 mo - long posterior cilary artery and anterior cilary artery start to form

4th mo - hyaloid begins to regress

6th mo - long posterior ciliary arteries extends and anastomoses with the anterior ciliary arteries to form the major arterial circle

the MAC will

send out branches forming the minor arterial circle

collarette

the anterior and posterior epithelium of the iris differntiates from

neural ectoderm which is actually the tip of the optic cup

the posterior iris epithelium is continuous with

the non pigmented epithelium of CB

the anterior iris epithelium is continuous with the

pigmented epithelium of CB

spinchter development

anterior epithelial cells migrate out of the epithelium into the position of the spnichter muscle

BEFORE development of the dilator

Dilator development

the base of the anterior epithelium then beings to form smooth msucle fibres that become the dilator

continues POST NATALLY

Pupil formation

- Decrease in blood flow to anterior vascular tunica Lentis

- Programmed cell death and phagocytoses by macrophages

- the ATVL atrophies back to the future collarette

dysfucntion of ATVL atrophy can lead to

epicapsular stars

remnants of the ATVL

deposits on the anterior capsule of the lens

Melanogenesis

production of melanin for color of the iris

melanosomes are _____ at birth

mature

Chromotophores develop

post natally

eumelanin

gives black and brown coloration

pheomelanon

gives brown and reddish tones

eye color develops

5-6 months postnatally

Postnatal times for iris

dilator: 5 months

Iris color: 5-6 months

aniridia

the rim of the optic cup fails to proliferate over the anterior surface of the lens

left with just a "stump" of an iris

poor vision and light sensitivity

filtration area is poorly developed in many patients and they develop glaucoma

typical colomboma

located inferiorly - this is associated with failure of the closure of the tip of the fetal fissure.

atypical colomboma

this is at a location away from inferiorly - associated with trauma, surgery

heterochromia complete

one iris eye color is different from the other

heterochromia incomplete

difference in iris coloration in the same eye

oculocutaneous albinism

more severe form

complete lack of melanin in skin, hair, eyes

iris has no pigement

appears almost pink because light often gets through the iris

can transilluminate

Ocular albinism

mainly effects the eyes

iris has some colir

usually a gray color

cannot transilluminate

mircrocoria

cogenitally very small pupil

abnormality of the dilator muscle development

sometimes associated with glaucoma due to malformation of the angle

Ectopic Pupil

very small deceneted pupil

usually bilateral and symmetrically displaced

caused by displaces or ectopic lens during development and iris grows less readiliy in one quadrant

CILIARY BODY

Blood Vessels and blood elements

mesodermal mesenchyme

Connective tissue stroma, melanocytes, and ciliary muscle

neural creset

pigmented and nonpigmented epithelium

neuroectoderm (optic cup)

4th wave of mesenchyme

forms the ciliary muscle

ciliary processes are formed from

as the vasculature of the ciliary body stroma forms it pushed on the double epithelial layer to form folds

these folds become processes

_______ ciliary muscles develop first

longitudinal

Ciliary muscle continues

to develop several years after birth!!!!

Zonule formatin

Ciliary epithelium synthesizes the zonules

Zonules attach to surface of capsule when equator of lens is in close contact with NPE

As gap develops and fibrillin synthesis continues - zonules stretch across the space