Download Anatomy 2 Hours - Utah Optometric Association

2/16/2016
Tear Film Layers
Basic Ocular
Anatomy
oil
aqueous
snot
Lynn E. Lawrence, CMSgt (ret),
CPOT, ABOC,COA
Healthy Tears
A complex mixture of proteins,
mucins, and electrolytes coated by
a lipid layer
What functions does each layer of the tear perform?
Lipid Secretion: Meibomian Glands
Left:
Transillumination of
eyelid showing
meibomian glands
• Antimicrobial proteins
• Growth factors & suppressors
of inflammation
Right:
Secretion of lipid
at lid margin
• Soluble mucin helps stabilize
tear film
• Electrolytes for proper
osmolarity (295-300)
– pH slightly alkaline (7.4)
• The lipid layer restricts evaporation to 5-10% of tear flow
– Also helps lubricate
Why is a tear salty tasting?
Where does a contact lens rest?
Lipid Secretion: Meibomian Glands
A Healthy Tear Film
What eye is this?
800 nm
8,000 nm
100 nm
(WC Posey, Diseases of the Eye, 1902)
Transillumination of
meibomian glands
How does the lipid layer aid in contact lens wear?
A healthy tear film is comprised of 3 layers: Mucin, Aqueous, and Lipid
(Transillumination image from Dry Eye and Ocular Surface Disorders, 2004)
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Two Primary Forms of Dry Eye
Oil & Water
Remember science class? Oil floats.
Oil does not mix with
water, but rather sits
on top of water.
Oil is what keeps
water from
evaporating.
800 nm
8,000 nm
100 nm
The two primary forms of dry eye are Evaporative Dry Eye, also known as
Meibomian Gland Dysfunction or MGD and Aqueous Dry Eye. The majority of
dry eye sufferers have MGD.
The Meibomian Glands
The Tear Film Structure In Our Eyes
The meibomian
glands are located
in the eyelids
The aqueous (water) layer
provides natureal lubrication
and is produced by the
lacrimal glands.
The aqueous layer is
protected by the lipid (oil)
layer that is produced by the
meibomian glands located in
the eyelids.
When your meibomian glands
do not produce sufficient oil,
water evaporates causing
burning, redness, dryness,
irritation and eye fatigue. This
is called Meibomian Gland
Dysfunction or MGD.
Meibomian Glands & Blinking
When we blink the meibomian glands express the
necessary protective oils
LipiView II: Interferometer
Blockages in the meibomian glands result in insufficient oil
to coat the tear film
Blinking stimulates the meibomian glands to secrete oils and spread a protective oil layer across the tear
film. When we partially blink the eyelids do not touch, so no pressure is applied at the meibomian glands to
release these oils. Over time the oils harden in the glands and blockages develop.
Avg LLT 35 nm
Avg LLT 90 nm
Avg LLT – Average Lipid
Layer Thickness (LLT) in
nanometers (nm).
Number less than 90
indicates increased
probability for MGD.
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LipiView II: Dynamic Meibomian Imaging
LipiView II: Partial Blink Analysis
A decrease in lipid layer thickness is
associated with incomplete blinking.
Increase in visual fatigue is associated with
incomplete blinking.
Meibomian gland structure is observed with Dynamic Meibomian Imaging (DMI). DMI produces three
images (surface illumination, transillumination and merged) to capture a comprehensive view of
meibomian gland structure.
If left untreated, the glands can shrink and deteriorate. The loss of glands is unlikely to be reversible.
Failure to treat blocked glands is likely to lead to further structural compromise.
Surface Illumination
Transillumination
Merged (Surface + Transillumination)
Presence of partial blinks greater than 40%
of total blinks is considered contributory to
dry eye condition.
If partial blinking is present, patient
education and blink training should be
considered.
Normal Gland Structure
Gland Truncation & Dilation
Severe Gland Drop Out
Intervention & Prevention
Meibomian Gland Evaluator
Upper Eyelid
Meibomian
Glands Over Time
Lower Eyelid
Temporal
Central
Prevention
Nasal
Meibomian gland function is evaluated by assessing how glands respond to
gentle force, imitating that of a deliberate blink.
Intervention
Current model of treatment
is interventional.
Future of MGD treatment
must be preventative.
NO OIL SECRETION (BLOCKED)
No oil is expressed using the MGE
CLEAR OIL SECRETION
Glands are functioning using the
MGE
Anatomy
OPAQUE SOLID SECRETION
Glands not functional; requires more
force than the MGE
Blue Eyes
• More Like to have:
–
–
–
–
Melanoma
AMD
Photophobia
Better with pain
What function does the pupil have?
http://www.msn.com/en-us/health/medical/7-things-your-eye-color-says-about-yourhealth/ar-BBiNSGg?li=AAa0dzB&ocid=IDMD&page=4&fullscreen=true#image=4
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The Eyelid
• 7 Layers of the eyelids
1. Skin-thinnest layer
2. Subcutaneous
connective tissue
3. Striated Muscle
4. Sub-muscular connective
tissue
5. Tarsal plate or fibrous layer
6. Smooth muscle
7. Conjunctiva
(Bulbar/Palpebral)
Eyebrows and Eyelashes
• Eyebrows
– Thickened ridge of skin with short
hairs
– Diverts perspiration
• Eyelashes
– Also protects
– Sebaceous glands at base of each
lash are called Glands of Zeis
which produce a lubricating fluid
• Fluid can harden and clog the
gland, producing a stye or
painless chalazion. If painful
and infected it is called an
external hordeolum
Cataracts (myotonia) are caused by?
How are Hordoleum and Chalazions treated?
Lacrimal Apparatus
• Sometimes a person cannot produce natural tears that they
might need some punctal plugs.
Anatomy and Physiology of the Eyeball
3 Layers
• Fibrous Layer
*Cornea
*Sclera
•
Vascular Layer
*Choroid
*Ciliary body
*Iris
•
Nerve Layer
*Retina
*Macula
*Optic nerve
What are the three main parts of the crystalline lens?
Sclera
• White in color
• Primary function is protection
• Pierced posteriorly by the optic
nerve
• Acts as insertion points for the
six EOMs
• Junction between the cornea
and sclera is called the Limbus
What is the total power of the eye?
What is the main function of each layer?
Conjunctiva
• An epithelial membrane which
covers the anterior sclera and
continues to the back surfaces
of the lids to form a
conjunctival sac
• Has blood vessels which can
burst and cause
subconjunctival hemorrhage
• Three parts
– Bulbar
– Palpebral
– Fornix - where bulbar and
palpebral meet
Name the mucus producing cell?
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Cornea
Cornea
What is it called when blood vessels
grow onto the cornea?
• Composed of 5 layers
– Epithelium…24 hr healing
•
•
•
•
What happens when a patient gets
a scar in the visual pathway?
•
•
•
•
•
Index of refraction is 1.37
Approximately .5mm in thickness
Transparent Organ (no blood vessels / avascular)
Primary function is refraction of light rays
Refractive power approx + 45.00 D
Outermost layer
5 cell layers thick
Heals very quickly
Does not scar
– Bowman's membrane- layer just under the epithelium NOTE: will
scar
– Stroma – middle tissue that forms 90% of the cornea
– Descemet's membrane- thin elastic layer deep in the cornea
– Endothelium - only one cell layer thick; lines undersurface of the
cornea, where it regulates corneal water content
What is the crossover point for the nasal optic nerves?
What cranial nerve is tied to corneal sensations?
Endothelial detail with nuclei
Confocal Scanner
Aqueous Humor
•
•
•
Epithelial detail with nuclei
•
Manufactured by ciliary body
Characteristics:
– Clear
– Watery consistency (99%
H2O)
Functions
– Refraction of light
– Intraocular Pressure (IOP)
– Probably nourishes
posterior surface of the
cornea and the crystalline
lens
Flows from posterior chamber
through the pupil into the
anterior chamber
Which cells do not regenerate Epithelium
or Endothelium?
How does aqueous flow out of anterior chamber?
Crystalline Lens
Crystalline Lens
...approx 12-14 diopters of power
• 3 things happen during accommodation:
– Pupils constrict
– Eyes converge
– Lens gets thicker
• Functions
– Refraction of light
– Accommodation
• The crystalline lens contains a high degree of
protein
• Focus adjustment of the
eye
• Presbyopia is the loss in
accommodation
– Changes in the lens protein causes the lens to lose its transparency
which is a condition termed "cataract"
– Aphakia is the absence of a lens. It can be removed during cataract
extraction
– First noticed around age
40. Due to a loss in
flexibility of the lens
Name the three main parts of the lens?
How much focusing power does the lens have?
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Ciliary Body
Iris
• Most anterior portion of the
vascular layer
• Gives the eye its color, i.e.
blue eyes, brown eyes, etc.
• Consists of blood vessels,
pigment and muscle tissue
• Regulates light
• Smaller with age
• Located near the base of
the iris and posterior to it
• Composed of blood
vessels and muscle fibers
(ciliary muscle)
• Cilliary process produces
aqueous
What does the sphincter muscle control?
Ciliary body is attached to suspensatory ligaments called?
Nerve Layer - Retina
Vitreous Chamber
• Functions:
• Visual Receptors are Cones and Rods
– Refraction of light
– Internal support
– Cones
• Produce color vision
• Give improved acuity
• Used in day vision = “Photopic” = normal and high levels of
illumination
• Spots in vision may be
floaters in the vitreous
– Rods…120 million
• Produce black and white vision
• Function in dim light = “Scotopic” = low level of illumination
– Cones and Rods… 6 million
• Used under mesopic vision = between scotopic and photopic
• Both rods and cones are used.
Post vitreous detachment
How many chambers are inside the eye?
The _____ is the strongest refractive media and has about ____ diopters of power.
The retina (Cranial Nerve II)
Pigment
epithelium
Vitreous
Which cranial nerve controls the superior oblique muscle?
The levator palpebrae raises the eyelid and is innervated by CN #?
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Retina – 10 layers
Outside of eye
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•
•
•
•
•
•
•
•
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Identification of Retinal Layers
NFL
Pigment epithelium
Rods
Cones
Outer plexiform layer
Horizontal cells
Bipolar cells
Amacrine cells
Inner plexiform layer
Ganglion cells
Nerve fiber layer
ILM
GCL
IPL
OPL
Stratus OCT™
IS/OS
NFL: Nerve Fiber Layer
ILM: Inner Limiting Membrane
GCL: Ganglion Cell Layer
RPE/CC
IS/OS: Junction of inner and outer
photoreceptor segments
RPE: Retinal Pigment Epithelium
CC: Choriocapillaris
Choroid
IPL: Inner Plexiform Layer
OPL: Outer Plexiform
Cross-sectional image of live tissue; a virtual biopsy
Vitreous (inside of eye)
Nerve Layer - Retina
• Optic nerve head (optic
disc)
– No receptors physiological blind spot
– Point of exit of optic
nerve
– Appears yellow
compared to the orange
retina
Nerve Layer - Retina
• Ora Serrata
– Land mark attachment site
for choroid and retina
– Most anterior portion of
retina
– Nearly all rods
How many layers are in the retina?
What is Pars Plana?
Anatomy and Physiology
of the extraocular muscles
New Advancement
• ARCUS II Retinal
Prosthesis
• Netherlands 2nd
• Patient is Jerone
Perk, has retinitis
pigmentosa
• Dr. Marco Mura,
MD
 The Extra-ocular Muscles (EOM)
 Organized into an umbrella-like
bundle among the orbital fat,
orbital blood vessels and
nerves
 Six muscles associated with eye
movements
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
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

Superior rectus (S.R.)
Inferior rectus (I.R.)
Medial rectus (M.R.)
Lateral rectus (L.R.)
Superior oblique (S.O.)
Inferior oblique (I.O.)
How many cranial nerves control these 6 muscles?
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Extra Ocular Muscles
Extraocular Muscles
• Medial Rectus
- Most powerful, adduction, CN
III
• Inferior Rectus
- Primary is depression, CN III
• Lateral Rectus
- Abduction, CN VI
• Superior Rectus
- Primary is elevation
What is the name of the point where the muscles come together?
Muscles and Function
Which muscle close the eye lid and is innervated by cranial #7?
Bony Orbit
• Openings of the orbit
– Purpose of openings
• LR6…SO4…3
–
–
–
–
–
–
• Transmit arteries and/or veins to and from the orbit
• Transmit nerves to and from the orbit
Rectus
Obliques
Intorsion
Extorsion
Elevation
Depression
– Types of openings
• Fissures (crevices/cracks)
• Foramina (holes)
– Major openings
• Optic foramen - II cranial nerve - Optic Nerve
• Supraorbital fissure - IV cranial nerve - Trochlear Nerve
The transition zone between the sclera and the cornea is called?
An obvious upward/superior deviation of the eye is called?
Orbit
1.
2.
3.
4.
5.
6.
Frontal bone…forehead
Ethmoid bone…weakest
Palatine bone…smallest
Zygomatic bone…strongest
Lacrimal bone
Maxillary bone
Cranial Nerves LR6SO4
3
Muscles
• Lateral rectus muscles
#6 …abducens nerve
• Superior Oblique #4
…trochlear nerve
• All other muscles are
controlled by #3 …
oculomotor nerve
The conjunctiva has two divisions, they are?
Name the 3 chambers of the internal eye?
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Anatomy Physiology
•
•
•
•
•
The Orbit
Bones, etc.
The Sinuses
Locations
Human Body Planes
External Structures
Eyelids
Conjunctiva
Eyelashes and Eyebrows
Lacrimal System
Visual Pathway Objectives
• Define the visual
pathway
• Identify structures in
the visual pathway
• Testing used for the
visual pathway
• Identify defects within
the visual pathway
Anisometropia occurs when there is a _____________?
The outer layer of the eyeball is called?
Visual Pathway
Visual Pathway
• Visual pathway has seven
structures
• Physical
• Physiological
• Psychological
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–
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–
–
–
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Retina
Optic Nerve
Optic Chiasm
Optic Tract
Lateral Geniculate Body (LGB)
Optic Radiations
Visual Cortex …where vision
occurs
What causes your physiological blind spot?
Aniseikonia occurs when an object viewed by one eye is _________?
Visual Pathway
Retina
• Divided into four quadrants like
the brain
• Fovea at exact center
• Optic nerve head is located in
nasal half
• Each quadrant sees the exact
opposite visual field
Antimetropia occurs when __________ ?
What is an exudate?
What is papilledema?
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Optic Chiasm
• Temporal fibers do
not cross
• Nasal fibers do cross
• Some fibers from the
macula cross while
others do not
What part of the brain does the vision occur?
Growth beneath Pituitary Gland
Visual Field Defects
• Common types of field
defects
– Blind spots - Areas of
blindness in the visual field
– Hemianopsia - Blindness in
one half of the visual field of
one or both eyes
• Homonymous - Involving the
nasal half of the visual field of
one eye and the temporal half
of the visual field of the other
eye
• Incongruous -
Homonymous heminopia
Incongruous homonymous
Binasal defect
An area of blindness within a visual field is called?
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Is this possible? You be the judge
Review Questions
• The point where the upper and lower eyelids meet is called
a. ora serrata
b. canthus
c. joint
d. sphinx
• The blockage of the meibomian gland is called the
___________ when it causes pain, and the _________ when
it does not cause pain.
Review Questions
• The eyelid will protect your eyes from…
a. blinking
b. dust particles
c. stray tears
d. a burning punctum
• What main muscles raises the eyelid?
• Name the five layers of the cornea in order
Review Questions
Review Questions
• The drain port for tears is called?
a. canal of Schlemm
b. punctum
c. lacrimal gland
d. zonnule of Zinn
• In what layer of the eye will chronic diseases normally manifest?
• What structure prevents a contact from going behind the globe of the
eye?
Review Questions
• What are the layers of a tear film?
• What is the most anterior part of the retina.
• What is the total power of the Cornea, the crystalline lens
assembly, and the overall eye?
• What is the most posterior layer of the retina?
• Where is tear mucin produced?
• Why is the tear film important in contact lens wear?
• The optic nerve is which cranial nerve?
• What function does the Canal of Schlemm have?
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Review
Review Questions
• Opia means what?
• Identify the name for the 3 parts of the conjunctiva
• What is the difference between a tropia and a phoria?
• In what layer of the eye will the retina be found?
• Avascular means what?
• What is the strongest bone of the bony orbit?
• How many extra-ocular muscles are oblique?
• What does the root word “papill” mean?
• What muscle of the lid would be involved in ptosis?
Review Questions
Review Questions
• _________ exist when the foveal lines of sight of the two eyes
do not point at the same object.
–
–
–
–
A. binocularity
B. strabismus
C. conjunctivitis
D. FB sensation
• Of the following all are anomalies of the binocular system
except:
–
–
–
–
A. strabismus
B. Amblyopia
C. anomalous correspondence
D. conjunctivitis
Review Questions
• Which test checks for eye movement and helps detect the
dominate eye?
–
–
–
–
A. muscle H
B. cover test
C. visual acuity
D. myopia
• Glaucoma screening test that used puff of air onto the eye
surface:
–
–
–
–
A. NCT
B. snellen
C. amsler grid
D. accommodation
• When the power of the crystalline lens correspond with axial
length of the eye, so that parallel light rays are appropriately
refracted to focus on the retina is called?
–
–
–
–
A. emmetropia
B. ammetropia
C. hyperopia
D. myopia
• An opacity of the crystalline lens is known as?
–
–
–
–
A. photophobia
B. cataract
C. edema
D. aphakia
Review Questions
• Which test uses Pseudo Isochromatic Plates?
– A. IOP
– B. color test
– C. cover/uncover
– D. snellen
• This checks the power of the eye:
– A. NCT
– B. taking case history
– C. Autorefractor
– D. taking blood pressure
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Review Questions
• Which test is used to check six cardinal position of gaze for
motility?
–
–
–
–
A. Muscle H
B. APD
C. Amsler Grid
D. Tropia
• Examination of the eye is performed by using a slit lamp or
another name for slit lamp is:
–
–
–
–
A. non-contact tonometer
B. biomicroscope
C. pupilometer
D. lensometer
Review Questions
• What is a good tear BUT?
• What device checks the brain-eye connection?
• What device measures the distance between
the pupils?
• What device measures corneal thickness?
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