Vision Science Exam 2

Middle (vascular) layer of the eye structures and name

Iris, ciliary body, choroid; called the uvea.

Iris anterior ocular structure

Crystalline lens

Small pupil vs large pupil terms

Small: Miosis; Large: Mydriasis

Average iris diameter

12 mm

Two iris zones divided by collarette

Pupillary and ciliary zones

Function of the iris

Limit light entering the eye using sphincter and dilator muscles.

Fuch's Crypts function

Depressions in the iris surface allowing aqueous to enter and exit stroma.

Three structures of the iris anterior border layer

Fibroblasts, melanocytes, collagen fibrils

Iris stroma composition (three structures)

Connective tissue, non-pigmented cells, pigmented cells

Iris sphincter muscle facts

Smooth muscle, in pupillary zone, constriction causes miosis, parasympathetic innervation.

Two structures of the iris epithelium

Anterior iris epithelium, posterior iris epithelium

Anterior iris epithelium components

Apical epithelium, basal epithelium (iris dilator)

Iris dilator muscle facts

Radial arrangement, contraction causes mydriasis, sympathetic innervation.

Most posterior layer of the iris

Posterior epithelium

Posterior iris surface structures (two)

Radial contraction furrows, deep structural furrows of Schwalbe

Structures determining iris color

Clump cells, melanocytes

Anatomical ciliary body divisions (two)

Pars plana, pars plicata

Physiological ciliary body divisions (two)

Ciliary muscle, ciliary epithelium

three types of smooth muscle fibers that make up the ciliary muscle

Longitudinal, radial, circular

Ciliary epithelium types and function

Pigmented and nonpigmented ciliary epithelium; secretes aqueous humor.

Choroid location

Internal to the sclera, external to the retina

Four layers of the choroid

Suprachoroid, choroidal stroma, choriocapillaris, Bruch's membrane

In which space of the choroid do the long posterior ciliary arteries and nerves travel from the posterior to the anterior globe

Suprachoroidal space

Choroidal stroma tiers (two)

Haller's layer (large vessels) and Sattler's layer (medium vessels)

Choriocapillaris facts

Specialized capillary bed, single fenestrated layer, contains pericytes.

Most internal layer of the choroid

Bruch's membrane

Structure transforming light energy to neural signal

Retina

Ten retinal layers (external to internal)

RPE, photoreceptors, ELM, ONL, OPL, INL, IPL, ganglion cell layer, NFL, ILM

Retinal layer where we find lysosomes that phagocytize discs from the outer portion of the photoreceptor cells

Retinal pigment epithelium (RPE)

Photoreceptor rods and cones summary

a. Molecules found in the disc membranes of the outer segment- RHODOPSIN

b. stalk that connects the outer and inner segments- CILIUM

c. structure of the ellipsoid- MITOCHONDRIA

d. what process occurs in the myoid- PROTEIN SYNTHESIS

e. sympathetic terminal of the rod cell- SPHERULE

f. sympathetic terminal of the cone cell- PEDICULE

g. Rods are specialized for- NIGHT, PERIPHERAL, BLACK AND GREY

h. Cones are specialized for- DAY, CENTRAL, COLOR

Molecules combining to create rhodopsin

Vitamin A (retinal) and opsin

External limiting membrane creation structures

Photoreceptor cells, Müller cells

Retinal layer for photoreceptor cell bodies

Outer nuclear layer

Outer plexiform layer synapses

Between photoreceptor cells, bipolar cells, and horizontal cells

Cells found in the inner nuclear layer

Bipolar, horizontal, amacrine, interplexiform neurons, neuroglial cells

Bipolar dendrites synapse with which cells?

Photoreceptor, horizontal cells

Bipolar axons synapse with which cells?

Ganglion, amacrine cells

Function of horizontal cells

Transfer information horizontally parallel to retinal surface

Function of amacrine cells

Help modulate information from bipolar cells to ganglion cells

Function of interplexiform neurons

Provide feedback between inner and outer retinal layers

Neuroglial cells function and three types

Provide support and structure to retinal tissue; Müller cells, microglial cells, astrocytes

Neuroglial cell involved in glucose metabolism

Müller cells

Phagocytic neuroglial cells wandering retinal layers

Microglial cells

Where are astrocytes found?

Inner retina in the nerve fiber and ganglion cell layers

Retinal layer where we find synapses between bipolar and ganglion cells

inner plexiform layer

Retinal cells classified by visual pathway termination

Ganglion cells

The nerve fiber layer is made up of the axons of what type of cells

Ganglion cells

Innermost layer of the retina

Internal limiting membrane

Two xanthophyll pigments in the macula

Lutein, zeaxanthin

Two retinal layers making up the optic disc

Nerve fiber layer, internal limiting membrane

What is an OCT?

Optical Coherence Tomography; a fast, non-invasive imaging test using light waves to take high-resolution, cross-sectional retinal pictures.

First branch off the ophthalmic artery

Central retinal artery

Retinal layer containing central retinal artery

Nerve fiber layer (NFL)

The lacrimal artery follows which EOM

Lateral rectus muscle

The superior and inferior branches of the long posterior ciliary arteries eventually become which arterial structures?

Major arterial circle of the iris

Short posterior ciliary arteries choroid structure

Arterial network

Blood seen in a subconjunctival hemorrhage originates from which artery?

Anterior ciliary artery

Blood in anterior chamber from major circle compromise

Hyphema

Arteries supplying orbital sinuses

Ethmoid artery

Artery supplying periorbita

Supraorbital artery

Medial palpebral arteries anastomose with branches of which artery to form the palpebral arcades

Lacrimal artery

Three arteries supplying forehead

Supraorbital, supratrochlear, anterior temporal

Three arteries supplying lacrimal sac

Dorsonasal, angular, maxillary

First arterial branch off external carotid artery

Facial artery

Artery supplying orbicularis muscle

Zygomatic artery

If orbital veins have no valves, how is blood flow directed?

Pressure gradients

Which vein drains the superior orbital structures

Superior ophthalmic vein

Vein draining blood from lacrimal sac

Inferior ophthalmic vein

Blood from the retina drains into which vein

Central retinal vein

Choroidal blood drains into which structures

Vortex veins

Superior and inferior petrosal sinuses drain into which large venous structures

Internal jugular vein

Cranial nerves supplying orbital sensory innervation

Optic (II) and Trigeminal (V)

Four motor cranial nerves of orbital contents/adnexa

Oculomotor (III), Trochlear (IV), Abducens (VI), Facial (VII)

Divisions of cranial nerve V

Ophthalmic, maxillary, mandibular

Nerves branching off division I of CN V

Nasociliary, frontal, lacrimal

Five branches of the nasociliary nerve

Sensory root from ciliary ganglion, long ciliary, anterior ethmoid, posterior ethmoid, infratrochlear

Nerve supplying caruncle and canaliculi

Infratrochlear nerve

Two branches of the frontal nerve

Supratrochlear, supraorbital

Condition diagnosed via redundant forehead innervation

Herpes Zoster Ophthalmicus

Temporal branch of ophthalmic division of CN V

Lacrimal nerve

Division II of CN V name

Maxillary nerve

Two branches of maxillary nerve

Infraorbital, zygomatic

Third division of CN V and area innervated

Mandibular nerve; lower face

CN and division innervating iris sphincter muscle

Oculomotor (III), inferior division

EOM innervated by CN IV

Superior oblique

CN innervating lateral rectus muscle

Abducens (VI)

CN and root innervating lacrimal gland

Facial (VII), small root

Two main structures of central nervous system

Brain, spinal cord

Peripheral nervous system three structures

Cranial nerves, spinal nerves, ANS

Two divisions of autonomic nervous system

Sympathetic, parasympathetic

Six ocular structures innervated by ANS

Iris muscles, ciliary muscle, eyelid smooth muscles, choroidal/conjunctival blood vessels, lacrimal gland

Sympathetic vs parasympathetic effects on ANS ocular structures

iris muscle: sympathetic = mydriasis; Parasympathetic = miosis

ciliary muscle: sympathetic = Inhibition; Parasympathetic = accommodation

smooth muscle of eyelids: sympathetic = wild palpebral fissure; Parasympathetic = no effect

choroidal blood vessels: sympathetic = constriction; parasympathetic = dilation

conjunctival blood vessels: sympathetic = constriction; parasympathetic = dilation

lacrimal gland: sympathetic = decrease production; Parasympathetic = increase production

Ocular sympathetic pathway overview

hypothalamus

Lateral column of cervical spinal cord

preganglionic fibers

• - leaves the spinal cord via ventral root

• - enters sympathetic ganglion chain

• - ascend sympathetic chain

• - synapse in superior cervical ganglion

postganglionic fibers

• - Leave ganglion from carotid plexus around internal carotid artery

• 1. CN → VI→ Nasociliary nerve→ long ciliary nerves→ iris dilator and ciliary muscle

• 2. CN → VI→ Nasociliary nerve→ ciliary ganglion (no synapse)→ short and long ciliary nerves→ choroidal and conjunctival blood vessels

• 3. Superior division CN III→ Muller’s muscle

• 4. Deep petrosal nerve→ vidian nerve→ pterygopalatine ganglion (no synapse)→ maxillary nerve→ zygomatic nerve→ lacrimal nerve→ Lacrimal gland

Ocular parasympathetic pathway to globe

Preganglionic

• Edinger-Westphal nucleus (midbrain)→ w/inf. div. CN III→ synapse in ciliary ganglion

Postganglionic

• Enter globe w/ short ciliary nn. → iris sphincter and ciliary m.

Ocular parasympathetic pathway to lacrimal gland

Preganglionic

• Lacrimal nucleus (pons) → w/ facial nerve → enter geniculate ganglion of facial nerve → leaves as greater petrosal nerve → vidian nerve → synapse in pterygopalatine ganglion

Postganglionic

• pterygopalatine ganglion → maxillary nerve → zygomatic nerve → lacrimal nerves → lacrimal gland

Three actions of accommodative convergence reaction

-Medial rectus muscle contracts to move image onto fovea

-Ciliary muscle contracts to keep image in focus

-Iris sphincter muscle constricts to decrease the size of the pupil for better depth of field

List the afferent and efferent steps in the pupillary light pathway

Afferent Pathway:

• i. Follows visual pathway up to posterior optic tract

• ii. Pupillary fibers exit in the posterior third of optic tract

• iii. Travel within brachium of superior colliculus

• iv. Synapse occurs in pretectal nucleus of midbrain

• v. Then split equally to ipsilateral and contralateral Edinger-Westphal nuclei

Efferent Pathway:

• i. Start at Edinger-Westphal nucleus and follow parasympathetic pathway to iris sphincter and ciliary muscle

• ii. Light in eye activates parasympathetic system causing iris sphincter to constrict

• iii. At the same time, the iris dilator is inhibited

• iv. This inhibition ends when light is removed

Structures in the visual pathway

Retina, optic nerve, optic chiasm, optic tract, LGN, optic radiations, primary visual cortex

Four segments of the optic nerve

Intraocular, intraorbital, intracanalicular, intracranial

Visual structure below 3rd ventricle and above pituitary

Optic chiasm