EyesEyes

External AnatomyExternal 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 AnatomyExternal Anatomy

Limbus – border b/t the cornea & scleraPalpebral fissures – elliptical open space b/t

lidsCanthus- corners of the eye where the lids

meet, inner & outerCaruncle – 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 partsA. Lacrimal gland, upper, outer corner of eye = tears

B. Puncta= inner canthus, tear drainage

C. Nasolacrimal duct= allows tears to drain from puncta to nasolacrimal sac. Tears then empty into the inferior meatus of the nose

Extraoccular musclesExtraoccular muscles

6 muscles – Attach eyeball to orbit– Straight and rotary movement– Four straight muscles

1. Superior rectus

2. Inferior rectus

3. Lateral rectus

4. Medial rectus

Two slanting/ oblique muscles5. 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 AnatomyInternal 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 & FieldsVisual 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 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 dataSubjective data

Vision difficultyPainStrabismus, diplopiaRedness, swellingWatering, dischargePast history ocular problemsGlaucoma

Glasses/ contactsMedicationsVision loss- coping mechanismsSelf–care behaviors

Objective data Objective data The Physical ExamThe 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 acuityTest visual acuitySnellen eye chartSnellen eye chart

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 visionTest for near vision

Vision screenerPeople > 40yrs or difficulty readingTest each eye with glassesHold card 14in. from eyesNormal result 14 / 14Test 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 fieldsTest visual fieldsConfrontation testConfrontation test

Compares peripheral vision with a tester who has normal peripheral vision

2 ft. apart, eye levelTester & client cover opposite eyes Tester advances finger in the periphery

– Superiorly ( 50 degrees )– Inferiorly ( 70 degrees )– Temporally ( 90 degrees )

Inspect Extraoccular Muscle Inspect Extraoccular Muscle FunctionFunction

Corneal light reflexCover testDiagnostic positions test

– 6 Cardinal Positions of Gaze

Inspect Extraocular Muscle Inspect Extraocular Muscle FunctionFunction

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 TestDiagnostic 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 Inspect External Structures

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 Anterior Eyeball Structures

Cornea & lensIris & pupil

– Size & shape– Pupillary light reflex– Accommodation

Cornea & LensCornea & Lens

Shine light from side across corneaCheck smoothness, clarityNormally no opacities

Iris and PupilIris 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 Ocular Fundus (internal surface of retina)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 lightPerson should focus on a distant object and

try & remain stillExaminer 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 reflexAdjust 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 backgroundRetinal background

Light – dark red normallyNote Lesions

– Size, shape, color, distribution

Macula & Fovea CentralisMacula & Fovea Centralis

Last in Funduscopic exam– 1 DD in size– Darker than rest of fundus– Foveal light reflex– Exam last

Retinal VesselsRetinal Vessels

Arteries Veins

COLOR Light red Dark red

SIZE Smaller 2/3 to 4/5 diam. Of veins

Larger

LIGHT REFLEX

Bright Inconspicuous

absent

Read Aging & Developmental Read Aging & Developmental ConsiderationsConsiderations

Review Abnormalities of the Eyes

3 most common causes of 3 most common causes of decreased visual functioning in decreased visual functioning in

the older adultthe older adultCataract (lens opacity)Glaucoma (increased ocular pressure) = loss

of peripheral visionMacular degeneration (breakdown of cells

in the macula lutea) = loss of central vision