Week 11 - Ciliary body, iris, optic nerve, choroid,

Fill in: Accommodation - When focusing on near, the ciliary muscle "?" and "?". The tension on the zonules "?" and they "?". Lens attains increased "?" and the anterior chamber becomes shallower.

contracts and moves forward, releases and they slacken, increased thickness

Accommodation...: Select one: a. Amplitude increases with age b. Is controlled via sympathetic innervation (CN III) c. None of these d. Response is produced through the contraction of the iris muscles e. Mechanism is linked closely with convergence and pupillary constriction responses

e

Which of the following statements is incorrect: Select one: a. Colobomas of the iris most frequently affect the inferior half of the iris b. Sphincter pupillae muscle is innervated by the parasympathetic fibers of the autonomic nervous system c. Iris heterochromia may be acquired after prolonged anterior segment inflammatory disease d. Dilator pupillae muscle is innervated by the sympathetic fibers of the autonomic nervous system e. Cranial nerve VII (Facial) innervates the muscles of the iris

e

What does the inner (non-pigmented) epithelium face towards?

posterior chamber and aqueous

What are the functions of the choroid?

provides nutrition to RPE and outer retina, regulates ocular temperature and absorbs excess light

Fill in: Accommodation - At rest (distance focus), the ciliary muscle is "?" and the zonules are "?" so the lens is '"?" convex.

relaxed, taut, less convex

What are the overall functions of the uveal tract?

retinal illumination control (iris), nourishment (CB and choroid), Aqueous humour production (CB) and accommodation (CB)

Fill in: Myelination of the optic nerve begins at the "?" region of the lamina. Myelin is secreted by "?" in the peripheral neurons and "?" in the CNS.

retrolaminar, schwann cells, oligodendrocytes

What determines iris colour?

the Melonocyte density in strom and anterior border layer of iris stroma

Fill in: Ciliary muscle tendons anchor the ciliary body to the "?" and act in "?"

sclera, accommodation

Fill in: ALL ciliary nerves pierce sclera and run with "?" posterior ciliary arteries

short

Fill in: Innervation of ciliary body - Parasympathetic fibers from Edinger-Wesphal nucleus, run as part of "?" nerves supply to CB and iris. Run in outer "?" and branch near "?". "?" supply to ciliary muscle.

short ciliary nerves, outer choroid, ora serrata, Major

What kind of muscle is the ciliary muscle?

smooth

What is a Choroidal Nevus?

Congenital aggregation of melanocytes (benign)

What is the pars plicata also known as?

Corona Ciliaris

What is the Lamina Cribrosa?

Cribriform plate, CT structure, 'sieve-like' mesh of collagen lamellae. Spans the posterior scleral foramen

T/F: Bruch's membrane thins with age

F - thickens

T/F: the pars plicata has roughly 10 ciliary processes

F: 70-80 ciliary processes

T/F: The front surface of the iris is heavily pigmented with many radial folds

F: back surface

T/F: The iris is bathed by aqueous humour on only the anterior side

F: both sides

T/F: The pupil is central in the iris

F: slightly inferior and nasal

The optic nerve runs from "?" to "?"

Globe to chiasm

Fill in: Innervation of ciliary body - Sensory - "?" branch of "?" nerve (CN"?") via "?" ciliary nerves.

Nasociliary branch of Ophthalmic nerve (CNV1) via Long ciliary nerves

What is Choroidal melanoma?

Neoplasm of uveal melanocytes (malignant)

What do the ganglion cell axons of the ONH form?

Neuro-Retinal Rim (NRR)

Which artery supplies the intracranial and intracanalicular ON?

Ophthalmic artery

What is another name for the Optic Papilla?

Optic nerve

What is the pars plana also known as?

Orbicularis Ciliaris

What are the 2 layers of the choroid stroma?

Outer (Haller's Layer) and Inner (Sattler's layer)

Persistant pupillary membrane image

Remnant of embryologic tunica lenticosa lentis

What are the functions of the ciliary body?

Secretion of aqueous humour, nourishment of lens, mucle power for accommodation, assistance with aqueous humour outflow, vitreous hyaluronic acid contribution

Blood supply to the choroid is derived from 3 arterial sources. What are these?

Short Posterior Ciliary arteries (x15-20), Long Posterior Ciliary arteries (x2) and Anterior Ciliary arteries (branches near to CB)

What are the spaces between the ciliary processes in the pars plicata called?

Valleys of Kuhnt

What is pupil block? What happens to the iris when this occurs?

When the iris and lens attach to each other. Iris will bow forward (Iris Bombe) due to elevated IOP.

The choroid is... : Select one: a. All of these b. Separated from inner sclera by the perichoroidal space c. Continuous with the ciliary body in the anterior segment d. A highly vascularised network, responsible for supplying nutrients to the outer retinal layers e. Drained by 4-8 vortex (vorticose) veins

a

Which of the following statements is correct: Select one: a. None of these b. Optic nerves are supplied by the anterior ciliary arteries c. Myelin is not essential for signal conductivity within the optic nerve d. Myelination of the optic nerve neurons begins in early embryological development, immediately following optic cup induction e. Each optic nerve contains 2-2.5 million ganglion cell projections

a

What are the 2 layers of epithelium on iris back surface?

anterior and posterior

Fill in: Iris embryology - Epithelium develops from "?" ("?"), between cornea and lens. Iris stroma develops from the same population of "?" that forms the corneal stroma and corneal endothelium. Iris sphincter and dilator muscles originate from the "?" instead of the mesoderm like most other muscles in the body.

anterior lip of optic cup (neuroextoderm) Migrating neural crest cells Neural ectoderm

Fill in: the iris is the "?"-most part of uveal tract and lies in front of "?" and "?"

anterior-most, CB and lens

Fill in: Ciliary processes secrete "?" into the posterior chamber

aqueous humour

The uveal tract...: Select one: a. Is composed of the ciliary body, retina and optic nerve b. Carries nutrients to the outer retinal layers c. None of these d. Is essentially avascular e. Is alone responsible to maintaining transparency in ocular tissue

b

Which of the following statements is correct: Select one: a. Choroidal blood vessels are non-fenestrated, and do not allow contents to leak into the surrounding tissue matrix b. Anterior surface of the iris does not contain an epithelium layer c. Pupil is the opening of the iris diaphragm, and is centered within the iris d. Sphincter pupillae muscle is located within the ciliary zone of the iris e. Aqueous humour bathes only the anterior surface of the iris

b

Which of the following statements is correct: Select one: a. Ciliary processes extend from the pars plicata region of the ciliary body b. All of these c. Pigmented ciliary epithelium borders the ciliary stroma d. Ciliary muscle modulates the accommodation response in the lens via the action of suspensory ligaments (zonules) e. Ora serrata marks the junction of sensory retina and ciliary body

b

Which of the following statements is correct: Select one: a. Myelination of the optic nerve begins at the prelaminar region b. Glaucoma is a disease characterized by a progressive loss of ganglion cell axons within the retina and optic nerve c. None of these d. Annulus of Zinn provides vascular supply to the optic nerve e. 2/3 of scleral fibers pierce the optic nerve at the lamina cribrosa

b

Which: Zonules run (in front of/between/behind) the ciliary processes and attach to lens

between

The blood-aqueous barrier is... : Select one: a. Dependent on the normal function of the retinal blood vessels b. Maintained by the reinforced anterior and posterior surface epithelium layers of the iris c. Frequently disturbed by inflammation in the anterior segment d. Enforced by tight junctions in the blood vessels of the cornea e. None of these

c

Fill in: The layer of choroidal blood vessel underneath the RPE is the "?"

choriocappilaris

What does the outer (pigmented) epithelium face towards?

ciliary body stroma

Fill in: Neuro-retina and RPE form 2 layer of the "?" epithelium. The retina continues as "?" epithelium while the RPE continues as "?" epithelium.

ciliary, non-pigmented, pigmented

Fill in: Seive-like mesh of "?" connective tissue from where the optic nerve exits the eye is known as "?".

collagen, Lamina Cribrosa

What are the 4 zones of the iris? Where are the Sphincter and Dilator Pupillae muscles?

1. Anterior border (surface) layer 2. Stroma (includes sphincter pupillae) 3. Anterior myoepithelium (includes dilator pupillae) 4. Posterior pigmented epithelium

What is Aniridia?

Congenital absence of iris

4 section of optic nerve diagram

1. Intraocular (ONH) within eye 2. Intraorbital from globe to apex of orbit 3. Intracanalicular ON passing via Optic Foramen 4. Intracranial On from optic canal to chiasm in cranium

What are the 4 layers of the choroid?

1. Outermost - Suprachoroid (lamina) 2. Stroma 3. Choriocapillaris 4. Innermost - Bruch's membrane

Clinical Q2: Iris heterochromia

12 yr old male, routine exam, no complaints

How many long ciliary arteries supply the ciliary body and what do they join to form?

2 and join to form the Major Arterial Circle

Fill in: The ciliary epithelium contains "?" layers of "?" epithelium

2 layers of cuboidal epithelium

Where is the optic nerve located in regards to the fovea?

3-4mm nasal

How many anterior ciliary arteries supply the ciliary body and what do they join to form?

7, join to form Intramuscular circle

How does the ciliary muscle alter with loss of accommodation with age (presbyopia)?

Altered ciliary muscle morphology: increased CT content, loss of longitudinal and oblique fibers and increase in circular fibers. Altered ciliary muscle contraction: less forward movement on contraction.

The Iris-Cornea junction is which Angle?

Anterior Chamber Drainage Angle

Which layer of the iris epithelium gives rise to the dilator pupillae muscle? What is this layer continuous with?

Anterior epithelium. continuous with the outer (pigmented) epithelium of ciliary body

What are the anterior, intermediate and posterior borders of the ciliary body?

Anterior: scleral spur/TM Intermediate: Iris root Posterior: Retina (ora serrata)

The pupil margin of the iris rests lightly on the lens to allow what?

Aqueous circulation

What is Coloboma?

Congenital absence of part of tissue (typically infero-nasal)

Non-fenestrated iris blood vessels form the what?

Blood-Aqueous barrier

Which artery supplies the postlaminar ON?

Branches of CRA and Pial arteries in periphery

What is another name for the Lamina Vitrea?

Bruch's membrane

Fill in: with age, the "?" may accumulate fatty/lipid plaques called "?", which can lead to "?".

Bruch's membrane, Drusen, age-related macular degeneration

The parasympathetic innervation of ciliary muscle in accommodation is by which CN?

CN III - oculomotor

Which artery supplies the orbital ON?

Central retinal artery (CRA) (central retinal vein as well)

Choroid perfusion is controlled by what?

Cholinergic receptors (BV dilation) and Adrenergic receptors (BV constriction)

Fill in: Venous return in the choroid is done via venules in "?". 4-8 "?" veins drain choroid and pierce sclera to join the "?" vein to the cavernous sinus and the "?" vein to the Pterygoid venous plexus

Choroid Stroma, Vortex veins, Superior Ophthalmic vein to the cavernous sinus and inferior ophthalmic vein to pterygoid venous plexus

Fill in: Venous return of ciliary body is achieved via the "?" veins

Choroidal Vortex veins

What is the middle structure of the uveal tract?

Ciliary body

Which artery supplies the pre-laminar and laminar ON?

Circle of Zinn-Haller + choroidal

Which layer of the ciliary muscle is closest to the lens equator?

Circular fibers (Mullers fibers)

What are the 4 sections of the optic nerve?

Intraocular (ONH), Intraorbital, Intracanalicular and Intracranial

What are the 3 components of the Uveal tract?

Iris (anterior), ciliary body (middle) and choroid (posterior)

Fill in: Innervation of ciliary body - Sympathetic - "?" nerves from "?" Ganglion. Accompany ciliary arteries and distribute along plexuses. "?" supply to ciliary muscle

Long ciliary nerves, Superior Cervical Ganglion, Minimal (to nil)

Which layer of the ciliary muscle is closest to the sclera?

Longitudinal fibers (Brucke's muscle)

What in the choroid/RPE absorbs stray light from rods/cones

Melanin

Name one of more differences between the ciliary muscle and most typical smooth muscles

Muscle bundles are: surrounded by flattened fibroblasts - not collagen, surrounded by continuous basement membrane, have more numerous Golgi, mitochondria and ER

What are the 3 sub-layers of the ciliary muscle?

Outermost: Longitudinal fibers (Brucke's muscle) Intermediate: Oblique/radial fibers Innermost: Circular fibers (Mullers fibers)

What is the origin of anterior zonules?

Pars plana

What innervates the Dilator Pupillae muscle?

Post-ganglionic fibers of Superior Cervical Ganglion via LONG ciliary nerves (sympathetic NS)

What innervates the sphincter pupillae muscle?

Post-ganglionic parasympathetic fibers (SHORT ciliary nerves) from CN III

What does the Optic nerve exit form?

Posterior Scleral Foramen

Where is the choroid thickest?

Posteriorly around ON

The Lamina Cribrosa divides the ONH into 3 regions, what are these? Where does myelination start?

Prelaminar, Laminar and Retrolaminar (myelination starts here)

What is the action of the sphincter pupillae muscle and what stimulates this?

Pupil constriction stimulated by bright light and accommodation

What is the action and stimuli of the Dilator Pupillae muscle?

Pupil dilation stimulated by darkness and fight/flight responses

What are the 2 zones the anterior border (surface) layer of the iris is divided into and what separates them?

Pupillary zone and Ciliary zone divided by the Collarette

What are the functions of the iris?

Regulates retinal illumination, pigmented barrier to excess light, contributes to Blood-Aqueous barrier

What is the Dilator Pupillae muscle composed of?

Single layer of myoepithelium from iris root to pupillary zone. Apical (epithlium) portion and Basal (muscular) portion which joins with the Iris posterior pigment epithlium

Which muscle is contained in the Iris stroma?

Sphincter Pupillae muscle

What are the 3 layers of the ciliary body and their sub-layers?

Stroma, Muscle and epithelium - inner (non-pigmented) and outer (pigmented)

T/F: Bruch's membrane is acellular and avascular

T

T/F: Choroid blood vessels get progressively smaller with the largest in Haller's layer and the smallest in the Choriocapillaris

T

T/F: the ciliary processes are highly vascular

T

T/F: the posterior pigmented epithelium or iris may extend into the anterior chamber drainage angle

T - iris processes

What is the ciliary body continuous with?

The choroid (posterior) and iris (anterior)

Fill in: "?" on the ciliary non-pigmented epithelium form a barrier between blood vessels of CB stroma and aqueous. This barrier is the "?" barrier

Tight junctions, blood-aqueous barrier

T/F: both ciliary epithelium layers have basement membranes facing outward - toward CB stroma and posterior chamber

True

Clinical Q: Glaucoma

Usually no symptoms, possible signs include: elevated IOP, enlarged cupping/NRR defects, disc hames, scleral rings/peripapillary atrophy

What does the posterior epithelium of the iris epithelium contain and what is it continuous with?

cuboidal cells packed with melanin, continuous with inner (non-pigmented) epithelium of ciliary body

Which of the following statements is correct: Select one: a. All of these b. Retinal blood vessels are fenestrated to allow diffusion of nutrients and plasma c. The foveal avascular zone (FAZ) receives no blood supply from the choroid d. Ultimate venous drainage of the choroid vessels is performed by the cavernous sinus and pterygoid venous plexus e. Typically, the choroid contains more than 10 vortex veins

d

Fill in: vascular supply to CB - CB stroma is "?"vascularised with "?" vessels

highly, fenestrated

Where is the ciliary muscle contained?

in the stroma of the ciliary body

Fill in: the Iris stroma is a highly vascular "?" matrix

loose CT

Which embryonic layer is the iris stroma derived from?

mesoderm (mesenchyma)

Fill in: Iris blood vessels are "?". Passive leakage of blood materials into aqueous is "?". This is termed the "?".

non-fenestrated, NOT allowed, Blood-Aqueous Barrier

Fill in: Retinal vessels are "?" (sealed) with "?" between RPE cells. This makes the "?".

non-fenestrated, tight junctions, Blood-Retina Barrier

Fill in: Anterior zonules - from pars "?" to "?" lens

pars plana to pre-equator lens

Fill in: Equatorial zonules - from pars "?" to "?" lens

pars plicata to equator of lens

Fill in: Posterior zonules - from pars "?" to "?" lens

pars plicata to post-equatorial lens

Fill in: the choroid is separated from the innermost sclera (lamina fusca) by "?". This connective tissue membranes span this space known as "?".

perichoroidal space, suprachoroidal lamina

Describe the ciliary stroma

specialised loose CT network (collagen/elastin), highly vascularised, with melanocytes, fibroblasts and mast cells. Has myelinated and non-myelinated nerves and contains the ciliary muscle

Fill in: The "?" muscle is present in the "?" and helps in pupil constriction, whereas the "?" muscle is present in the "?" and helps in pupil dilation

sphincter pupillae, stroma, dilator pupillae, myoepithelium

Fill in: the optic nerves are extensions of the brain's "?" matter

white