Lynn E. Lawrence, CMSgt (ret),
CPOT, ABOC
Tear Film Layers
oil
aqueous
snot
What functions does each layer of the tear perform?
Healthy Tears
•
Antimicrobial proteins
•
Growth factors & suppressors
of inflammation
•
Soluble mucin helps stabilize
tear film
•
Electrolytes for proper
osmolarity (295-300)
– pH slightly alkaline (7.4)
Why is a tear salty tasting?
A complex mixture of proteins,
mucins, and electrolytes coated
by a lipid layer
Lipid Secretion: Meibomian Glands
Left:
Transillumination of
eyelid showing
meibomian glands
Right:
Secretion of lipid
at lid margin
• The lipid layer restricts evaporation to 5-10% of tear flow
– Also helps lubricate
Where does a contact lens rest?
Lipid Secretion: Meibomian Glands
What eye is this?
(WC Posey, Diseases of the Eye, 1902)
Transillumination of
meibomian glands
How does the lipid layer aid in contact lens wear?
(Transillumination image from Dry Eye and Ocular Surface Disorders, 2004)
Anatomy
What function does the pupil have?
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)
How are Hordoleum and Chalazions treated?
 Eyebrows
Eyebrows and Eyelashes
 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?
Lacrimal Apparatus
 Sometimes a person cannot produce natural tears that they
might need some punctal plugs.
What are the three main parts of the crystalline lens?
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 is the main function of each layer?
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?
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?
Cornea
What is it called when blood vessels
grow onto the cornea?
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
What is the crossover point for the nasal optic nerves?
Cornea
 Composed of 5 layers
 Epithelium…24 hr healing




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 cranial nerve is tied to corneal sensations?
Harminder Dua June 2013
Endothelial detail with nuclei
Confocal Scanner
Epithelial detail with nuclei
Which cells do not regenerate Epithelium
or Endothelium?
Aqueous Humor
 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
How does aqueous flow out of anterior chamber?
Crystalline Lens
...approx 12-14 diopters of power
 Functions
 Refraction of light
 Accommodation


Focus adjustment of the
eye
Presbyopia is the loss in
accommodation

First noticed around age 40.
Due to a loss in flexibility of
the lens
Name the three main parts of the lens?
Crystalline Lens
 3 things happen during accommodation:
 Pupils constrict
 Eyes converge
 Lens gets thicker
 The crystalline lens contains a high degree of protein
 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
How much focusing power does the lens have?
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
What does the sphincter muscle control?
Ciliary Body
 Located near the base of
the iris and posterior to
it
 Composed of blood
vessels and muscle fibers
(ciliary muscle)
 Cilliary process produces
aqueous
Ciliary body is attached to suspensatory ligaments called?
Vitreous Chamber
 Functions:
 Refraction of light
 Internal support
 Spots in vision may be
floaters in the vitreous
Post vitreous detachment
How many chambers are inside the eye?
Nerve Layer - Retina
 Visual Receptors are Cones and Rods
 Cones
 Produce color vision
 Give improved acuity
 Used in day vision = “Photopic” = normal and high levels of
illumination
 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.
The _____ is the strongest refractive media and has about ____ diopters of power.
Which cranial nerve controls the superior oblique muscle?
The retina (Cranial Nerve II)
Pigment
epithelium
Vitreous
The levator palpebrae raises the eyelid and is innervated by CN #?
Retina – 10 layers










Outside of eye
Pigment epithelium
Rods
Cones
Outer plexiform layer
Horizontal cells
Bipolar cells
Amacrine cells
Inner plexiform layer
Ganglion cells
Nerve fiber layer
Vitreous (inside of eye)
Identification of Retinal Layers
NFL
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
Cross-sectional image of live tissue; a virtual biopsy
Choroid
IPL: Inner Plexiform Layer
OPL: Outer Plexiform
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
What is Pars Plana?
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?
New Advancement
 ARCUS II Retinal
Prosthesis
 Netherlands 2nd
 Patient is Jerone Perk,
has retinitis
pigmentosa
 Dr. Marco Mura, MD
http://www.newjerseynewsroom.com/science-updates/bionic-eye-implantallows-blind-man-to-see
Anatomy and Physiology
of the extraocular muscles
 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






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?
Extra Ocular Muscles
What is the name of the point where the muscles come together?
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
Which muscle close the eye lid and is innervated by cranial #7?
Muscles and Function
 LR6…SO4…3
 Rectus
 Obliques
 Intorsion
 Extorsion
 Elevation
 Depression
An obvious upward/superior deviation of the eye is called?
Extraocular Muscles
 Superior Oblique (SO)- has 3 functions; intorsion, depression and
abduction; innervated by the 4th (trochlear) cranial nerve
 Inferior Oblique (IO)- 3 functions; extorsion, elevation, and abduction;
innervated by the 3rd (oculomotor) cranial nerve
Proper alignment and muscle balance of the eyes is called?
Extraocular Muscles
 Medial Rectus (MR)- moves the eye inward from the
straight-ahead position (adduction); innervated by the 3rd
(Oculomotor) cranial nerve
 Lateral Rectus (LR)- moves the outward (abduction)
from the straight-ahead position; innervated by the 6th
(Abducens) cranial nerve
 Inferior Rectus (IR)- 3 functions; depression, extorsion, and
adduction; innervated by the 3rd (Oculomoter) cranial nerve
A definite and obvious turning of the eye is called?
Ocular Motility
 Version - a conjugate movement of the 2 eyes. Both eyes
remain parallel during the movement
 Vergence - A disjunctive movement of the 2 eyes
 Convergence

Near triad of accommodation, pupil constriction, and convergence
 Divergence
A constant tendency for the eyes to turn from the norm is called?
Muscle Balance Testing
 Cover Test
 Cover/uncover
 Alternating cover
 Hirschberg Test
 Location of corneal reflex
Which test checks for direction when using the cover test?
Extraocular Muscles
 Medial Rectus
 Toward the nose (adduction)
 Lateral Rectus
 Away from the nose (abduction)
 Superior Rectus
 Up;towards the nose (elevation)
 Inferior Rectus
 Down;away from the nose (depression)
How many extra ocular muscles are there?
Extraocular Muscles
 Superior Oblique
 Rotates the top of the eye toward the
nose;moves eye down
 Inferior Oblique
 Rotates the top of the eye away from the nose;
moves eye up
Where is the insertion points for these muscles?
Bony Orbit
 Openings of the orbit
 Purpose of openings


Transmit arteries and/or veins to and from the orbit
Transmit nerves to and from the orbit
 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?
Orbit
1.
2.
3.
4.
5.
6.
Frontal bone…forehead
Ethmoid bone…weakest
Palatine bone…smallest
Zygomatic bone…strongest
Lacrimal bone
Maxillary bone
The conjunctiva has two divisions, they are?
Cranial Nerves LR6SO4
Muscles
 Lateral rectus muscles
#6 …abducens nerve
 Superior Oblique #4
…trochlear nerve
 All other muscles are
controlled by #3 …
oculomotor nerve
Name the 3 chambers of the internal eye?
3
Anatomy Physiology
 The Orbit
- Bones, etc.
 The Sinuses
- Locations
 Human Body Planes
 External Structures
- Eyelids
- Conjunctiva
- Eyelashes and Eyebrows
 Lacrimal System
The outer layer of the eyeball is called?
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 _____________?
Visual Pathway
 Physical
 Physiological
 Psychological
What causes your physiological blind spot?
Visual Pathway
 Visual pathway has seven
structures
 Retina
 Optic Nerve
 Optic Chiasm
 Optic Tract
 Lateral Geniculate Body (LGB)
 Optic Radiations
 Visual Cortex …where vision
occurs
Aniseikonia occurs when an object viewed by one eye is _________?
Visual Pathway
Antimetropia occurs when __________ ?
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
What is an exudate?
What is papilledema?
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?
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
 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 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?
Review Questions
 What are the layers of a tear film?
 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?
Review
 Opia means what?
 What is the difference between a tropia and a phoria?
 Avascular means what?
 How many extra-ocular muscles are oblique?
 What does the root word “papill” mean?
Review Questions
 Identify the name for the 3 parts of the conjunctiva
 In what layer of the eye will the retina be found?
 What is the strongest bone of the bony orbit?
 What muscle of the lid would be involved in ptosis?
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
 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 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
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
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?