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 Anatomy External 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 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 Superior rectus Inferior rectus Lateral rectus Medial rectus

Two slanting/ oblique muscles Superior 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 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 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 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

Record the normal response to these tests as 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 Larger LIGHT REFLEX Bright 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