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Eyes
External Anatomy

Sensory Organ for vision
-Situated in bony, orbital cavity for
protection
– Eyelids= shades that add protection form injury,
strong light , dust
– Eyelashes= hairs to filter dust & dirt
External
External
Anatomy
Anatomy
Limbus – border b/t the cornea & sclera
 Palpebral fissures – elliptical open space b/t
lids
 Canthus- corners of the eye where the lids
meet, inner & outer
 Caruncle – sm. Fleshy mass containing
sebaceous glands at inner canthus


Within the upper eyelid
–
–
Tarsal plates, connective tissue gives upper lid
shape
Meibomian glands, in the plates, lubricate the
lids, stops overflow of tears, airtight seal
when lids closed

Exposed part of the eye
– Conjunctiva, folded envelope b/t eyelids &
eyeball



thin mucous membrane, transparent protective
covering of the exposed part of the eye.
Palpebral conjunctiva lines the lids, is clear but has
sm .bld. Vessels
Bulbar conjunctiva is over eyeball, white sclera
show through, merges at limbus with cornea

Cornea – clear, covers & protects iris &
pupil

Lacrimal apparatus – irrigates conjunctiva
& cornea
–
3 parts
A.
B.
C.
Lacrimal gland, upper, outer corner of eye = tears
Puncta= inner canthus, tear drainage
Nasolacrimal duct= allows tears to drain from
puncta to nasolacrimal sac. Tears then empty into
the inferior meatus of the nose
Extraoccular muscles

6 muscles
–
–
–
Attach eyeball to orbit
Straight and rotary movement
Four straight muscles
1.
2.
3.
4.
Superior rectus
Inferior rectus
Lateral rectus
Medial rectus

Two slanting/ oblique muscles
5. Superior
6. Inferior
Humans have a Binocular, single – image
visual system – Eyes normally move as a
pair
•
Eye movement stimulated by Cranial
Nerves
• III Oculomotor
• IV Trochlear
• VI Abducens
Internal Anatomy

The eye has 3 layers, the outer & inner
layer can be viewed using opthalmascope
1.
Sclera (outer layer) tough, protective,
white covering connects with the  Cornea – transparent, protects pupil &
iris – helps focus light on retina
2.
Middle layer
 Choroid – dark pigmentation to prevent internal
light reflection, supplies bld. to retina
 Pupil – PERRLA
 Lens – biconvex disc, transparent, thickness
controlled by ciliary body, bulges = near;
flattens = distant
 Anterior chamber – posterior to cornea,
anterior to iris & lens, has aqueous humor
supplies nutrients & drains wastes
3.
Inner layer – Retina – visual receptive
layer – light waves changed to nerve
impulses
 Retinal structures

Optic disc – retinal fibers meet & form optic
nerve, nasal side of retina, creamy yellow orange
to pink, round or oval shape, physiologic cup
inside the disc for bld.vessels to enter & exit

Retina vessels – paired arteries & veins
Macula – temporal side of fundus, darker pigmented
region, surround the fovea centralis
 Fovea Centralis- area of sharpest & keenest vision,
Very sensitive to light

Visual Pathways & Fields

Objects reflect light
 Rays refracted by cornea, aqueous humor, lens,
vitreous body and onto retina.
 Light stimulus is changed to nerve impulses, travel
thru optic nerve to visual cortex in occipital lobe
 Image on retina is upside down & reversed. At the
optic chiasm retinal fibers cross over. Right side of
brain looks at left side of world.
Visual reflexes

Pupillary light reflex – bright light = constriction
– Direct light reflex
– Consensual light reflex
Fixation – ability to track an object & keep image
on the fovea, can be impaired by drugs, alcohol,
fatigue & inattention
 Accomodation – for near vision = pupil
constriction & convergence of eyes

Subjective data

Vision difficulty
 Pain
 Strabismus, diplopia
 Redness, swelling
 Watering, discharge
 Past history ocular problems
 Glaucoma

Glasses/ contacts
 Medications
 Vision loss- coping mechanisms
 Self–care behaviors
Objective data
The Physical Exam

Preparation
– Position- sitting, head at eye level

Equipment
– Snellen eye chart- visual acuity
– Handheld visual screener-near vision
– Opaque card
– Penlight
– Applicator stick
– Ophthalmoscope
Test visual acuity
Snellen eye chart

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


Stand 20 ft. from chart
Glasses / contacts (Document )
Remove eye wear, retest
Normal visual acuity is 20/20 – top # is distance
person is standing from the chart
Vision
20/30 refer to opthalmologist or
optometrist
If unable to see largest letters, move to 10 feet –
record as 10/200
Test for near vision

Vision screener
 People > 40yrs or difficulty reading
 Test each eye with glasses
 Hold card 14in. from eyes
 Normal result 14 / 14
 Test using any available reading material if
no card available

Presbyopia is a normal physiological
change in near vision occurs with aging =
note if the person moves the card farther
away
Test visual fields
Confrontation test

Compares peripheral vision with a tester
who has normal peripheral vision
 2 ft. apart, eye level
 Tester & client cover opposite eyes
 Tester advances finger in the periphery
– Superiorly ( 50 degrees )
– Inferiorly ( 70 degrees )
– Temporally ( 90 degrees )
Inspect Extraoccular Muscle
Function

Corneal light reflex
 Cover test
 Diagnostic positions test
– 6 Cardinal Positions of Gaze
Inspect Extraocular Muscle
Function

Corneal Light Reflex ( The Hirschberg Test)
assesses parallel eye alignment
– Shine light toward person’s eyes
– Tell to stare directly ahead
– Hold light 12 in. away
– Light should reflect on both corneas in same
spot

Cover Test- detects deviated alignment
– Stare straight at examiner’s nose
– Cover 1 eye of the person being examined with opaque
card
– Normally the uncovered eye should maintain a steady,
fixed gaze
– Covered eye- should stare straight ahead when covered
& then uncovered. If muscle weakness exists the
covered eye will relax and then jump to fixed position
when uncovered..
Diagnostic Positions Test

6 cardinal positions of gaze –
– Determines muscle weakness during movement
– Person must hold head steady
– Follow movement of object (examiner’s finger, pen etc)
only with eyes
– Hold object 12 in. from person
– Move thru each position, clockwise, hold , then back to
center
– Normal response= parallel tracking with both eyes

During this test be aware of Nystagmus-fine
jerky movement seen around the iris
 Mild nystagmus in extreme lateral gaze is
normal but not normal in any other position
Inspect External Structures



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General – movement & facial expression
(squinting?)
Eyebrows – 2(bilateral), symmetrical (look the
same; move the same)
Eyelids & Lashes – present, approximate when
closed, no redness, swelling, discharge, lesions?
Eyeballs- alignment, ? Protrusion? Sunken?
Conjunctiva & Sclera – moist, glossy, clear, white
sclera

Eversion of the upper eyelid FYI – we will
not do this examine in lab see pg. 312 for
technique – usually done for complaint of
eye pain due to foreign body

Lacrimal Apparatus
– Person looks down
– Using thumbs, slide outer part of upper lid
along bony orbit
– Note redness or swelling
– Press index finger against lacrimal sac at inner
canthus
– Normal response is slight eversion of lower lid,
no tearing or discharge
Anterior Eyeball Structures

Cornea & lens
 Iris & pupil
– Size & shape
– Pupillary light reflex
– Accommodation
Cornea & Lens

Shine light from side across cornea
 Check smoothness, clarity
 Normally no opacities
Iris and Pupil

Iris = flat, round, regular, even color
bilaterally.
 Pupils = PERRLA
– Resting size norm = 3-5mm
– 5% population have pupils of 2 diff. Sizes
called Anisocoria

Pupillary Light Reflex
– Darken room
– Person gazes straight ahead
– Advance light from the side
 Direct light reflex
 Consensual light reflex
– Measure pupil size before & after light reflex
– Measurement R3/1 L3/1 =both pupils measure
3mm in resting state & 1mm with light

Accomodation
– focus on distant object -dilatation of pupils
– Shift gaze to near object – pupils constrict &
converge

Record the normal response to these tests as

PERRLA = Pupils Equal, Round, React
to Light and Accomodation
Ocular Fundus (internal
surface of retina)

Use Opthalmoscope- try keeping both eyes
open- practice looking at a ring on your
finger. Become familiar with the instrument
before you examine your partner’s eyes

Diopter of opthalmoscope
– Black numbers = +diopter, focus on near
objects
– Red numbers = - diopter, focus on further
objects

Use ophthalmoscope in darkened room =
dilates pupils
Remove examiner’s and person’s eyeglasses
but contact lenses may be left in.
 Select lg. White aperture light
 Person should focus on a distant object and
try & remain still
 Examiner hold ophthalmoscope in Right
hand to right eye to eamine person’s right
eye

Begin 10in away at 150 lateral angle &
advance
 Keep sight of red reflex
 Adjust lens to +6 as you advance till your
foreheads almost touch. Adjust diopter to
focus.

– Normal vision set at 0. Nearsighted use red #s.
Farsighted use black.
Retinal background
Light – dark red normally
 Note Lesions

– Size, shape, color, distribution
Macula & Fovea Centralis

Last in Funduscopic exam
– 1 DD in size
– Darker than rest of fundus
– Foveal light reflex
– Exam last
Retinal Vessels
Arteries
Veins
COLOR
Light red
Dark red
SIZE
Smaller 2/3 to
4/5 diam. Of
veins
Bright
Larger
LIGHT
REFLEX
Inconspicuous
absent
Read Aging & Developmental
Considerations
Review Abnormalities of the Eyes
3 most common causes of
decreased visual functioning in
the older adult

Cataract (lens opacity)
 Glaucoma (increased ocular pressure) = loss
of peripheral vision
 Macular degeneration (breakdown of cells
in the macula lutea) = loss of central vision