The Eyes Have it by BrittanyGibbons

VIEWS: 396 PAGES: 61


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 &

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
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

Sclera (outer layer) tough, protective, white covering connects with the  Cornea – transparent, protects pupil & iris – helps focus light on retina


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


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
 

– Position- sitting, head at eye level

– Snellen eye chart- visual acuity – Handheld visual screener-near vision – Opaque card – Penlight – Applicator stick – Ophthalmoscope

Test visual acuity Snellen 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 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



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

   

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


– focus on distant object -dilatation of pupils

– Shift gaze to near object – pupils constrict &


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


Light red Smaller 2/3 to 4/5 diam. Of veins Bright

Dark red Larger


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

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