Upload
miracle-moorehouse
View
219
Download
2
Embed Size (px)
Citation preview
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