Eyes External Anatomy l Sensory Organ for vision

Eyes

External Anatomy l 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 Anatomy

l Limbus – border b/t the cornea & sclera l Palpebral fissures – elliptical open space b/t lids l Canthus- corners of the eye where the lids meet, inner & outer l Caruncle – sm. Fleshy mass containing sebaceous glands at inner canthus

l 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

l 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. l Palpebral conjunctiva lines the lids, is clear but has sm. bld. Vessels l Bulbar conjunctiva is over eyeball, white sclera show through, merges at limbus with cornea l

l Cornea pupil – clear, covers & protects iris &

l 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 l 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

l 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 l 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 Ø Cornea – transparent, protects pupil & iris – helps focus light on retina

2. Middle layer Ø Choroid – dark pigmentation to prevent internal light reflection, supplies bld. to retina Ø Pupil – PERRLA Ø Lens – biconvex disc, transparent, thickness controlled by ciliary body, bulges = near; flattens = distant Ø 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 v Retinal structures v v 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 v Fovea Centralis- area of sharpest & keenest vision, Very sensitive to light v

Visual Pathways & Fields Objects reflect light l Rays refracted by cornea, aqueous humor, lens, vitreous body and onto retina. l Light stimulus is changed to nerve impulses, travel thru optic nerve to visual cortex in occipital lobe l 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. l

Visual reflexes l 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 l Accomodation – for near vision = pupil constriction & convergence of eyes l

Subjective data l Vision difficulty l Pain l Strabismus, diplopia l Redness, swelling l Watering, discharge l Past history ocular problems l Glaucoma

l Glasses/ contacts l Medications l Vision loss- coping mechanisms l Self–care behaviors

Objective data The Physical Exam l Preparation – Position- sitting, head at eye level l Equipment – Snellen eye chart- visual acuity – Handheld visual screener-near vision – Opaque card – Penlight – Applicator stick – Ophthalmoscope

Test visual acuity Snellen eye chart l l l 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 l Vision screener l People > 40 yrs or difficulty reading l Test each eye with glasses l Hold card 14 in. from eyes l Normal result 14 / 14 l Test using any available reading material if no card available

l 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 l Compares peripheral vision with a tester who has normal peripheral vision l 2 ft. apart, eye level l Tester & client cover opposite eyes l Tester advances finger in the periphery – Superiorly ( 50 degrees ) – Inferiorly ( 70 degrees ) – Temporally ( 90 degrees )

Inspect Extraoccular Muscle Function l Corneal light reflex l Cover test l Diagnostic positions test – 6 Cardinal Positions of Gaze

Inspect Extraocular Muscle Function l 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

l 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 l 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

l During this test be aware of Nystagmus-fine jerky movement seen around the iris l Mild nystagmus in extreme lateral gaze is normal but normal in any other position

Inspect External Structures l l l 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

l 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

l 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 l Cornea & lens l Iris & pupil – Size & shape – Pupillary light reflex – Accommodation

Cornea & Lens l Shine light from side across cornea l Check smoothness, clarity l Normally no opacities

Iris and Pupil l Iris = flat, round, regular, even color bilaterally. l Pupils = PERRLA – Resting size norm = 3 -5 mm – 5% population have pupils of 2 diff. Sizes called Anisocoria

l Pupillary Light Reflex – Darken room – Person gazes straight ahead – Advance light from the side Direct light reflex l Consensual light reflex l – Measure pupil size before & after light reflex – Measurement R 3/1 L 3/1 =both pupils measure 3 mm in resting state & 1 mm with light

l Accomodation – focus on distant object -dilatation of pupils – Shift gaze to near object – pupils constrict & converge l Record the normal response to these tests as l PERRLA = Pupils Equal, Round, React to Light and Accomodation

Ocular Fundus (internal surface of retina) l 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

l Diopter of opthalmoscope – Black numbers = +diopter, focus on near objects – Red numbers = - diopter, focus on further objects l Use ophthalmoscope in darkened room = dilates pupils

l Remove examiner’s and person’s eyeglasses but contact lenses may be left in. l Select lg. White aperture light l Person should focus on a distant object and try & remain still l Examiner hold ophthalmoscope in Right hand to right eye to eamine person’s right eye

l Begin 10 in away at 150 lateral angle & advance l Keep sight of red reflex l 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 l Light – dark red normally l Note Lesions – Size, shape, color, distribution

Macula & Fovea Centralis l 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 l Cataract (lens opacity) l Glaucoma (increased ocular pressure) = loss of peripheral vision l Macular degeneration (breakdown of cells in the macula lutea) = loss of central vision