Occular Anatomy: Choroid

functions of the choroid

1. Nourish outer 1/3 of retina

2. Absorb excess light that passes through RPE

3. Provides protective canal for vessels and nerves

4. stabilizes ocular temperature

5. contributes to Bruch's membrane

Tje choroid lies inbetween

the retina and the sclera

choroid extends tom the

ora serrata to the optic nerve

the choroid is _____ around the optic nerve

discontinuous

Thickness trends

1. thicker in younger individuals, thins as we age

2. Thicker in posterior pole vs thinner in periphery (2x as thick)

3. Thicker in people with hyperopia (shorter axial length)

thinner in people with myopia (longer axial length)

Choroid Color

dark color promotes absorbing of extra light

dark color is from melanocytes

3 layers of blood vessels

1. Choriocapillaris

2. Sattler's layer

3. Haller's layer

Choriocapillaris

inner layer

small vessles

Sattler's layer

middle layer

medium vessels

Haller's layer

outer layer

larger vessels

Layers of the Choroid

Bruch's membrane

Choriocapillaris

Stroma (Sattler's layer and Haller's layer)

Lamina fuscia

Lamina Fusca

suprachoroid lamina

transition zone between scleral and choroid

Lamina Fusca contains

layers of long interconnected branched ribbon like processess

part sclera: collagen and fibroblasts

part choroid: melanocytes

does not hae own blood supply

Suprachoroidal space

potential space

carries long posterior ciliary arteries, long posterior ciliary nerves, and short posterior ciliary nerves from the posterior to anterior potion of the globe

can be separated by blood during disease or injection

anterior fusca is the site of

the muscle star insertions of the longitudinal muscles fibers from the ciliary body

(drainage from trabecular meshwork)

choroid arterial blood supply

1, short posterior ciliar arteries

2. long posterior ciliary arteries

3. andterior ciliary arteries

Short posterior ciliary arteries

branches of the opthalmic artery

penetrate emissara

penetrate lamina fusca and outer layers of choroid

contribute to the choriocapilaris up tp the equator (not anteriorly)

Long Posterior Ciliary Arteries

enter suprachoroidal space between macula and equator

at ora serrata it branches into 3-5 branches

anastomose with anterior ciliary arteries - Major arterial circle of iris

some will feed anteriir aspects of choriocapillarues

Anterior ciliary arteries

branch of muscular artery (branch of opthalmic)

recti muscles

go into eye through anterior emissaria

anastomose with long posterior ciliary arteries --> MAC of iris

anterior choriocapilaris

choroidal stroma

primarily supportive in nature

haller's layer

Sattler's layer

arteries and veins encircled by

type 1 collagen

choroid has one of the highest blood flows of any tissue in the body!!!!!!

this supports the functions of nourishing the outer retina and maintaining ocular temperature

other cells in the stroma

melanocytes

fibrocytes

macrophages

plasma cells

lymphocytes

masts cells

Haller's Layer

the vessels are organized into tiers, those with larger lumina occupying the outer layer

Sattler's layer

vessels from Haller's layer branch as they pass inward

medium sized

nonfenestrated vessles which are primarily arterioles

Choriocapillaris

sattler's layer branches to form the choriocapillaris

supports retina

choriocapilaris is denested and thcikes under the

macula!!!!!

remember we have an avascular zone in the fovea

Choriocapillaris anatomy

single layer of capillaries

- fenestrated face the retina

- wide lumina: these are the largest capillaries in the eye

Choroid Nerve Sympathetic does

vasocontrict --> decreases choroidal blood flow

Choroid Nerve Parasympathetic does

vasodialate --> increase chordial blood flow

Choroid Nerve Sympathetic Innervation

nasociliary (V1) --> long posterior ciliary nerve

OR

superior cervical ganglion --> ciliary ganglion --> short posterior ciliary nerve

Choroid Nerve Parasympathetic Innervation

EW --> Ciliary ganglion--> short posterior ciliary nerve

vasodilate vessels (THIS IS OPPOSITE OF THE IRIS)

venous drainage

vortex veins drain choroid and some anterior uvea --> superior and inferior ophthalmic veins --> cavernous sinus

vortex ampulla

major venous drainage vessels in Haller's layer

Bruch's membranse

an extracellular matrix with contributions from the RPE and the choroid

Bruchs membrane extends from the

optic disc to the ora serrata

Bruch's membrane thickest at _____ and tapers _____

optic disc (2-4 um)

periphery (1-2 um)

Layers or bruch's membrane

RPE basement membranse

Inner collagenous

Central Elastic

Outer Collagenous

Choricapillaris basement memrbane

Bruch's membrane functions

1. Physical barrier between retina and choroid

2. Molecular Regulation

3. Structural support to RPE

Normal aging changes

bruch's membrane thickens with age

AND

basal lamina deposits in collageous zones

decrease permeability

decreased ability to facilitate metabolic exchange with retina

Abnormal Aging Changes

Drusen --> Dry Age related macular degeneration

Drusen

excessive calcification and deposits in the inner collagenous zone of Bruch's membrane