EyeEye

Sensory organ of visionSensory organ of vision Protected in bony orbital cavity, Protected in bony orbital cavity,

surrounded by a cushion of fatsurrounded by a cushion of fat Eyelids protect the eye from injury, Eyelids protect the eye from injury,

strong light, & dust.strong light, & dust. Upper lid larger & more mobileUpper lid larger & more mobile Eyelashes are short hairs in double or Eyelashes are short hairs in double or

triple rows that curve outward to filter triple rows that curve outward to filter dust & dirtdust & dirt

Palpebral fissure – Palpebral fissure – elliptical opening elliptical opening between eyelids. between eyelids. When closed, lid When closed, lid margins approximate. margins approximate. When open, upper lid When open, upper lid just covers part of the just covers part of the iris, lower lid is just iris, lower lid is just at the limbus (border at the limbus (border between cornea & between cornea & sclera)sclera)

Canthus – corner of Canthus – corner of the eye. At the inner the eye. At the inner canthus, a small canthus, a small fleshy mass fleshy mass containing sebaceous containing sebaceous glandsglands

Conjunctiva – Conjunctiva – transparent protective transparent protective covering, a thin mucous covering, a thin mucous membranemembrane

Folds like an envelope Folds like an envelope between the eyelids & between the eyelids & the eyeballthe eyeball

Palpebral – lines the lids, Palpebral – lines the lids, is clear with many small is clear with many small blood vesselsblood vessels

Bulbar – overlays the Bulbar – overlays the eyeball, white sclera eyeball, white sclera shows throughshows through

At the limbus, At the limbus, conjunctiva merges with conjunctiva merges with the corneathe cornea

Cornea – covers & Cornea – covers & protects the iris & pupilprotects the iris & pupil

Lacrimal appartus – Lacrimal appartus – provides the eye provides the eye with constant with constant irrigation, keeps irrigation, keeps conjunctiva & cornea conjunctiva & cornea moist & lubricatedmoist & lubricated

Lacrimal gland – at Lacrimal gland – at the upper, outer eye; the upper, outer eye; secretes tearssecretes tears

Puncta – tears drain Puncta – tears drain here, then down into here, then down into nasolacrimal duct to nasolacrimal duct to the inferior meatus the inferior meatus of the noseof the nose

Extraocular MusclesExtraocular Muscles 6 muscles attach the 6 muscles attach the

eyeball to its orbit & give eyeball to its orbit & give the eye straight & rotary the eye straight & rotary movementmovement

4 rectus muscles are 4 rectus muscles are superior, inferior, lateral superior, inferior, lateral & medial rectus muscles & medial rectus muscles (for straight)(for straight)

2 oblique muscles are 2 oblique muscles are superior & inferior (for superior & inferior (for slanting)slanting)

Each muscle is Each muscle is coordinated with the one coordinated with the one in the other eye to ensure in the other eye to ensure that movement is that movement is conjugate or parallel conjugate or parallel (humans see only one (humans see only one image)image)

Cranial NervesCranial Nerves Extraocular muscles Extraocular muscles

are stimulated by are stimulated by cranial nervescranial nerves

Abducens (6) – lateral Abducens (6) – lateral rectus muscle rectus muscle (abducts the eye)(abducts the eye)

Trochlear (4) – Trochlear (4) – superior oblique superior oblique musclemuscle

Oculomotor (3) – Oculomotor (3) – innervates all the restinnervates all the rest

Internal Eye AnatomyInternal Eye Anatomy Made up of 3 layersMade up of 3 layers Outer fibrous scleraOuter fibrous sclera Middle vascular Middle vascular

choroidchoroid Inner nervous retinaInner nervous retina

Accessible to Accessible to examination are sclera examination are sclera anteriorly & retina anteriorly & retina through through ophthalmoscope ophthalmoscope

Sclera Sclera

Tough, protective white coveringTough, protective white covering Anteriorly – smooth, transparent Anteriorly – smooth, transparent

cornea covering iris & pupilcornea covering iris & pupil Cornea refracts incoming light rays Cornea refracts incoming light rays

so that they focus on the retinaso that they focus on the retina Cornea is sensitive to touch – wisp of Cornea is sensitive to touch – wisp of

cotton stimulates a bilateral blink cotton stimulates a bilateral blink reflex called the corneal reflexreflex called the corneal reflex

Choroid Choroid Vascularized, delivering blood to the Vascularized, delivering blood to the

retinaretina Anteriorly – ciliary body of iris which Anteriorly – ciliary body of iris which

controls the thickness of the lens. Iris controls the thickness of the lens. Iris functions as a diaphragm varying the functions as a diaphragm varying the amount of light coming through the pupil amount of light coming through the pupil onto the retinaonto the retina

Muscle fibers contract the pupil in bright Muscle fibers contract the pupil in bright light & for near vision; dilate the pupil in light & for near vision; dilate the pupil in dark & looking fardark & looking far

Pupil – round & regular, 3-5 mmPupil – round & regular, 3-5 mm

Lens – a biconvex disc just posterior to Lens – a biconvex disc just posterior to pupil & keeps the viewed object focused pupil & keeps the viewed object focused on the retina. It bulges when focusing on the retina. It bulges when focusing on near objects & flattens for far objectson near objects & flattens for far objects

Anterior chamber – behind the cornea, Anterior chamber – behind the cornea, in front of the iris & lens. Contains in front of the iris & lens. Contains aqueous humor, a continuous flow that aqueous humor, a continuous flow that delivers nutrients to surrounding tissue delivers nutrients to surrounding tissue & drains wastes. Intraocular pressure is & drains wastes. Intraocular pressure is determined by a balance btw amount of determined by a balance btw amount of aqueous produced & resistance to its aqueous produced & resistance to its outflowoutflow

Retina Retina

Retina is the visual receptor layer of Retina is the visual receptor layer of the eyethe eye

Light waves changed into nerve Light waves changed into nerve impulsesimpulses

Can be viewed through Can be viewed through ophthalmoscopeophthalmoscope

Internal EyeInternal Eye

Can view optic disc, retinal vessels, Can view optic disc, retinal vessels, background, & maculabackground, & macula

Optic disc – fibers from retina converge Optic disc – fibers from retina converge to form optic nerve. View on nasal side to form optic nerve. View on nasal side of retina. Creamy – orange to pink in of retina. Creamy – orange to pink in color. Round to oval in shape. Distinct color. Round to oval in shape. Distinct margins (esp. on temporal side). margins (esp. on temporal side). Physiological cup is smaller circular Physiological cup is smaller circular area inside the disc where blood vessels area inside the disc where blood vessels enter & exitenter & exit

Retinal vessels are paired artery & Retinal vessels are paired artery & vein extending to each quadrant. vein extending to each quadrant. Smaller towards the peripherySmaller towards the periphery

Arteries – brighter red & narrow, Arteries – brighter red & narrow, with a thin light reflexwith a thin light reflex

Veins – little thicker & darker redVeins – little thicker & darker red General background – varies in color General background – varies in color

depending on skin colordepending on skin color

Macula – on temporal Macula – on temporal side, slightly darker side, slightly darker than background. than background. Receives light from Receives light from the center of the the center of the visual fieldvisual field

Fovea centralis – area Fovea centralis – area of sharpest, keenest of sharpest, keenest vision. Pinpoint vision. Pinpoint glistening dot in the glistening dot in the center of the maculacenter of the macula

Subjective DataSubjective Data

Vision difficulty (blurring, spots, Vision difficulty (blurring, spots, decreased acuity)decreased acuity)

PainPain Strabismus (crossing eyes)Strabismus (crossing eyes) Redness, swellingRedness, swelling Watering, dischargeWatering, discharge Hx eye problemsHx eye problems Glasses or contactsGlasses or contacts Self-care Self-care