Chapter 15 EYES PDF

Chapter 15 EYES External Anatomy  Bony orbital cavity surrounded by cushion of fat protects eye  Palpebral fissure:  Elliptical open space between eyelids  Lower lid margin, at limbus, borders between cornea and sclera  Canthus: corner of eye, angle where lids meet Inner canth...

Chapter 15 EYES External Anatomy  Bony orbital cavity surrounded by cushion of fat protects eye  Palpebral fissure:  Elliptical open space between eyelids  Lower lid margin, at limbus, borders between cornea and sclera  Canthus: corner of eye, angle where lids meet Inner canthus: caruncle is small fleshy mass containing sebaceous glands  Tarsal plates  contain meibomian glands, which are modified sebaceous glands that secrete an oily lubricating material onto lids External Anatomy 3  Conjunctiva Transparent protective covering of the eye  Cornea covers and protects the iris and pupil  Lacrimal apparatus provides irrigation to the eye External Anatomy of the Eye Extraocular Muscles  Six muscles attach eyeball to its orbit and direct eye to points of a person’s interest  Give eye both straight and rotary movement  Each muscle is coordinated, or yoked, with one in other eye ensuring that when two eyes move, their axes always remain parallel, called conjugate movement Four straight, or rectus, muscles are superior, inferior, lateral, and medial rectus muscles Two slanting, or oblique, muscles are superior and inferior muscles  Parallel axes are important because human brain has a binocular, single-image visual system Extraocular Muscles  Movement of the extraocular muscles stimulated by three cranial nerves Cranial nerve VI: abducens nerve, innervates lateral rectus muscle, which abducts eye Cranial nerve IV: trochlear nerve, innervates superior oblique muscle Cranial nerve III: oculomotor nerve, innervates all the rest: the superior, inferior, and medial rectus and the inferior oblique muscles Muscle Attachments Direction of Movement Internal Anatomy  Eye: a sphere of three concentric coats Outer fibrous sclera Middle vascular choroid Inner nervous retina Inside retina is transparent vitreous body. Only parts accessible to examination are sclera anteriorly and retina through ophthalmoscope. Three Concentric Coats Internal Anatomy: Outer Layer  Sclera: tough, protective, white covering  Continuous anteriorly with smooth, transparent cornea, which covers iris and pupil  Cornea: part of refracting media of eye, bending incoming light rays so that they will be focused on inner retina  Corneal reflex—contact with a wisp of cotton stimulates a blink in both eyes  Trigeminal nerve, cranial nerve V, carries afferent sensation into brain.  Facial nerve, cranial nerve VII, carries efferent message that stimulates blink. Internal Anatomy: Middle Layer  Choroid: has dark pigmentation to prevent light from reflecting internally and is heavily vascularized to deliver blood to retina functions as a diaphragm, varying opening at its  Iris: center, the pupil  Muscle fibers of iris contract pupil in bright light and to accommodate for near vision  Dilate pupil when light is dim and for far vision Internal Anatomy: Middle Layer  Pupil:round and regular; size determined by balance between parasympathetic and sympathetic chains of autonomic nervous system  Stimulation of parasympathetic branch, through cranial nerve III, causes constriction of pupil  Stimulationof sympathetic branch dilates pupil and elevates eyelid  Pupil size also reacts to amount of ambient light and to accommodation or focusing an object on retina Internal Anatomy: Middle Layer  Lens: biconvex disc located just posterior to pupil  Transparent; it serves as a refracting medium, keeping a viewed object in focus on retina  Anteriorand posterior chambers contain clear, watery aqueous humor produced continually by ciliary body Continuous flow of fluid serves to deliver nutrients to surrounding tissues and to drain metabolic wastes  Intraocularpressure determined by balance between amount of aqueous produced and resistance to outflow Internal Anatomy: Inner Layer  Retina:the visual receptive layer of eye where light waves change into nerve impulses  Retinal structures viewed through ophthalmoscope are optic disc, retinal vessels, general background, and macula  Optic disc: area in which fibers from retina converge to form optic nerve  Located toward nasal side of retina, it has characteristics specific to color, shape and margins Internal Anatomy: Inner Layer 16  Retinal vessels: normally include a paired artery and vein extending to each quadrant  Macula: located on temporal side of fundus Slightlydarker pigmented region surrounding fovea centralis, area of sharpest and keenest vision Receives and transduces light from center of visual field Visual Pathways and Visual Fields  Light rays are refracted through transparent media, the cornea, aqueous humor, lens, and vitreous body, striking the retina  Retinatransforms light stimulus into nerve impulses conducted to visual cortex Image formed on retina is upside down and reversed All retinal fibers collect to form optic nerve but maintain same spatial arrangement At optic chiasm, fibers from both visual fields cross over Left optic tract now has fibers from left half of each retina, and right optic tract contains fibers only from right; thus, right side of brain looks at left side of the world Visual Pathways Visual Reflexes  Pupillarylight reflex: normal constriction of pupils when bright light shines on retina  Subcortical reflex arc with no conscious control  Fixation: a reflex direction of eye toward an object attracting a person’s attention  Image fixed in center of visual field, the fovea centralis Visual Reflexes 20  Accommodation: adaptation of eye for near vision  Accomplishedby increasing curvature of lens through movement of ciliary muscles  Although lens cannot be observed directly, the following components of accommodation can be observed: Convergence (motion toward) of the axes of the eyeballs Pupillary constriction Developmental Competence: Aging Adults  Changes in eye structure  loss of elasticity, fat & muscle tissue atrophy &decreased tear production  Presbyopia  Lens loses elasticity, becoming hard and glasslike, which decreases ability to change shape to accommodate for near vision by age 40 to 45  Visual acuity may diminish gradually after age 50, and more so after age 70  Floaters appear from accumulation of debris Developmental Competence: Aging Adults  Most common causes of decreased visual functioning in older adults are the following: Cataract formation Lens opacity, resulting from a clumping of proteins in lens Diabetic retinopathy (DR) Oxidative damage & inflammation of the retina leading to blindness Developmental Competence: 23 Aging Adults  Glaucoma Increased intraocular pressure leading to optic nerve compression  Age-related macular degeneration (AMD) Degeneration of cells in macula of retina leading to loss of central vision Genetics and Environment  Culturally based variability present in color of iris and retinal pigmentation  By age 80, most individuals in the US have cataracts or have had cataract surgery Family history & environment are risk factors  Glaucoma incidence increases with age. Black Americans 40 years & older are at highest risk, followed by Hispanic/Latinos & Whites (NIH, 2021) Genetics and Environment  Age-related macular degeneration Increase seen in White Americans over the age of 75 (NIH,2021) Diet & smoking are modifiable risk factors  Visual impairment (VI) Not being able to see letters on the eye chart at line 20/40 or below (NIH, 2021) Genetics and Environment 26  Due to uncorrected refractive error  Mostcommon eye problems in children uncorrected refractive errors (nearsightedness, farsightedness & astigmatism) Visual screening is crucial to detect strabismus (“cross-eye”) & amblyopia (“lazy eye”) Subjective Data  Vision difficulty: decreased acuity, blurring, blind spots  Pain  Strabismus, diplopia  Redness, swelling  Watering, discharge Subjective Data 28  History of ocular problems  Glaucoma  Use of glasses or contact lenses  Patient-centered care  Terms: Myopia – Near sighted Hyperopia – Far sighted Vision Difficulty Questions  Anydifficulty seeing or any blurring? Blind spots? Come on suddenly or slowly? One eye or both?  Constant, or does it come and go?  Doobjects appear out of focus or clouding of objects?  Do spots move in front of your eyes? One or many? In one or both eyes? Vision Difficulty Questions 30  Any halos, rainbows, rings around objects?  Any blind spot? Does it move as you shift your gaze? Any loss of peripheral vision?  Any night blindness? Pain Questions  Any eye pain? Please describe.  Come on suddenly?  Quality: burning or itching? Or sharp, stabbing pain; pain with bright light? A foreign body sensation? Or deep aching? Or headache in brow area? Strabismus, Diplopia, Redness, and Swelling  Strabismus, diplopia: Any history of crossed eyes? Now or in the past? Does this occur with eye fatigue? Ever see double? Constant, or does it come and go? In one eye or both?  Redness, swelling Any redness or swelling in eyes? Any infections? Now or in past? When do these occur? In a particular time of year? Watering, Discharge and Past History  Watering, discharge  Any watering or excessive tearing?  Any discharge? Any matter in the eyes? Is it hard to open your eyes in the morning? What color is the discharge?  How do you remove matter from eyes?  Past history of ocular problems  Any history of injury or surgery to eye? Any history of allergies? Glaucoma, Eyeglasses, and Contact Lenses  Glaucoma  Have you ever been tested for glaucoma? What were the results?  Do you have any family history of glaucoma?  Use of glasses or contact lenses  Do you wear glasses or contact lenses? How do they work for you?  Last time your prescription was checked? Was it changed?  Ifyou wear contact lenses, are there any problems such as pain, photophobia, watering, or swelling?  How do you care for contacts? How long do you wear them? How do you clean them? Do you remove them for certain activities? Patient-Centered Care  Last vision test? Ever tested for color?  Anyenvironmental conditions at home or at work that may affect your eyes? If so, do you wear goggles to protect your eyes?  What medications are you taking? Systemic or topical? Any specifically for eyes? Patient Centered Care 36  Do you smoke?  Ifyou have experienced a vision loss, how do you cope? Do you have books with large print, books on audio tape, braille?  Do you maintain living environment the same?  Do you sometimes fear complete loss of vision? Additional History for Aging Adults  Have you noticed any visual difficulty with climbing stairs or driving? Any problem with night vision?  When was last time tested for glaucoma?  Any aching pain around eyes? Any loss of peripheral vision?  If you have glaucoma, how do you manage your eyedrops?  Is there history of cataracts? Any loss or progressive blurring of vision?  Do your eyes ever feel dry or burning? What do you do for this?  Any decrease in usual activities, such as reading or sewing? Objective Data  Preparation  Position a person standing for vision screening; then sitting up with head at your eye level.  Equipment needed:  Snellen eye chart  Handheld visual screener  Opaque card or occluder  Penlight  Ophthalmoscope  Applicator stick (occasionally) Test Near Vision  For those who report increasing difficulty reading  Test near vision with handheld vision screener with various sizes of print (e.g., a Jaeger card)  Hold card in good light about 35 cm (14 inches) from the eye; this distance equals print size on 20-foot chart  Test each eye separately, with glasses on  Normal result is “14/14” in each eye, read without hesitancy and without moving card closer or farther away  When no vision screening card is available, ask the person to read from a magazine or newspaper  Confrontation Test  Gross measure of peripheral vision; compares the person’s peripheral vision with yours  We do not perform this test Corneal Light Reflex  Also known as the Hirschberg test  Assess parallel alignment of eye axes by shining a light toward the person’s eyes  Direct the person to stare straight ahead as you hold the light about 30 cm (12 inches) away  Note reflection of light on corneas; should be in exactly same spot on each eye Diagnostic Positions Test  Leading patient through six cardinal positions of gaze: Follow movement of penlight or object proceeding clockwise Assess for potential EOM muscle weakness, nystagmus, or lid lag General Inspection and Eyebrows  General  Already you will have noted the person’s ability to move around room, with vision functioning well enough to avoid obstacles and to respond to your directions  Alsonote facial expression; relaxed expression accompanies adequate vision  Eyebrows  Look for symmetry between the two eyes  Normally eyebrows are present bilaterally, move symmetrically as expression changes, and have no scaling or lesions Eyelids, Lashes, and Eyeballs  Eyelids and lashes  Upper lids normally overlap superior part of iris, and approximate completely with lower lids when closed  Note that eyelashes are evenly distributed along lid margins and curve outward  Eyeballs  Eyeballs are aligned normally in their sockets with no protrusion or sunken appearance  Blacks normally may have slight protrusion of eyeball beyond supraorbital ridge Conjunctiva and Sclera  Ask the person to look up; using thumbs, slide lower lids down along orbital rim, being careful not to push against eyeball  Inspectexposed area; eyeball should look moist and glossy  Numerous small blood vessels normally show through transparent conjunctiva  Otherwise, conjunctivae clear and show normal color of structure below; pink over lower lids and white over sclera  Note any color change, swelling, or lesions  Be aware of ethnic variations Lacrimal Apparatus  Ask the person to look down; with thumbs, slide outer part of upper lid up along bony orbit to expose under lid; inspect for any redness or swelling  Normally puncta drain tears into lacrimal sac  Presenceof excessive tearing may indicate blockage of nasolacrimal duct  Check by pressing index finger against sac, just inside lower orbital rim, not against side of the nose  Pressurewill slightly evert lower lid, but there should be no other response to pressure Cornea and Lens  Shinelight from side across cornea, and check for smoothness and clarity Oblique view highlights any abnormal irregularities in corneal surface  Thereshould be no opacities (cloudiness) in cornea, anterior chamber, or lens behind the pupil Do not confuse an arcus senilis with an opacity; arcus senilis is normal finding in aging persons Iris and Pupil  Iris normally appears flat, with round regular shape and even coloration  Note size, shape, and equality of pupils; normally pupils appear round, regular, and of equal size in both eyes  To test pupillary light reflex  Darken room and ask person to gaze into distance; this dilates pupils; advance a light in from side and note response  Normally you will see constriction of same-sided pupil (a direct light reflex) and simultaneous constriction of the other pupil (a consensual light reflex)  In acute care setting, pupil size is measured in millimeters before and after the light reflex Iris and Pupil  Test for accommodation by asking the person to focus on a distant object  This dilates pupils; then have the person shift gaze to near object, such as your finger held about 7 to 8 cm (3 inches) from nose  Normal response includes  pupillary constriction  convergence of axes of eyes  Record normal response to all these maneuvers as PERRLA, or Pupils Equal, Round, React to Light, and Accommodation Inspection of Ocular Fundus  Ophthalmoscope enlarges view of eye  We do not perform this inspection  Inspection of Optic Disc  Mostprominent landmark is optic disc, located on nasal side of retina; one half disc diameter  We do not perform this examination Retinal Vessels  Only place in body where you can view blood vessels directly  Many systemic diseases that affect vascular system show signs in retinal vessels  Follow a paired artery and vein out to periphery in four quadrants, noting these points:  Number: paired artery and vein pass to each quadrant; vessels look straighter at nasal side  Color: arteries brighter red than veins; also have arterial light reflex, with thin stripe of light down middle  A:V ratio: ratio comparing artery-to-vein width is 2:3 or 4:5  Caliber: arteries and veins show a regular decrease in caliber as they extend to periphery Eversion of the Upper Eye Lid  Used when one suspects foreign body or eye pain  Procedure may cause apprehension; therefore, use directed, deliberate approach. Multi-step procedure using applicator stick  Inspect for color change, swelling, lesion, or evidence of foreign body Developmental Competence  Aging adult  Visual acuity Perform same examination as described in adult section Central acuity may decrease, particularly after 70 years of age; peripheral vision may be diminished  Ocular structures Eyebrows may show loss of outer one third to one half of hair because of decrease in hair follicles; remaining brow hair is coarse As a result of atrophy of elastic tissues, skin around eyes may show wrinkles or crow’s feet; upper lid may be so elongated as to rest on lashes, resulting in pseudoptosis Developmental Competence  Aging adult  Ocular structures Eyes may appear sunken from atrophy of orbital fat; orbital fat may herniate, causing bulging at lower lids and inner third of upper lids Lacrimal apparatus may decrease tear production, causing eyes to look dry and lusterless and the person to report a burning sensation Pingueculae commonly show on sclera Developmental Competence  Aging adult  Ocular structures  Cornea may look cloudy with age  Arcus senilis is commonly seen around cornea.  Gray-white arc or circle around limbus due to deposition of lipid material  As more lipids accumulate, cornea may look thickened and raised, but arcus has no effect on vision  Xanthelasma: soft, raised yellow plaques occurring on lids at inner canthus  They commonly occur around fifth decade of life and more frequently in women, occur with both high and normal levels of cholesterol, and have no pathologic significance Developmental Competence  Aging adult  Ocular structures  Pupils small in old age; pupillary light reflex may be slowed  Lens loses transparency and looks opaque  Ocular fundus  Retinal structures generally have less shine; blood vessels look paler, narrower, and attenuated; arterioles appear paler and straighter, with a narrower light reflex  Drusen,or benign degenerative hyaline deposits, are normal development on retinal surface  Often symmetrically placed in eyes with no effect on vision Abnormal Findings: Extraocular Muscle Dysfunction  Asymmetric corneal light reflex  Strabismus Esotropia—inward turning of eye Exotropia—outward turning of eye  Cover test  Uncovered eye  Covered eye  Diagnostic positions test  Paralysis indicates cranial nerve dysfunction. Abnormal Findings: EyeLid Abnormalities  Periorbital edema  Exophthalmos (protruding eyes)  Enophthalmos (sunken eyes)  Ptosis (drooping upper lid)  Upward palpebral slant  Ectropion (eversion)  Entropion (inversion) Abnormal Findings: Lesions on the Eyelids  Blepharitis (inflammation of the eyelids)  Chalazion  Hordeolum (stye)  Dacryocystitis (inflammation of the lacrimal sac)  Basal cell carcinoma Pupil Abnormalities  Unequal pupil size—Anisocoria  Monocular blindness  Constricted and fixed pupils—Miosis  Dilated and fixed pupils—Mydriasis  Argyll Robertson pupil  Tonic pupil (Adie’s pupil)  Cranial nerve III damage  Horner’s syndrome Abnormal Findings: Visual Field  Retinal damage Macula central blind area (e.g., Diabetes) Localized damage (Blind spot – scotoma) Increasingintraocular pressure (Glaucoma) Retinal detachment (shadow or diminished Vision Abnormal Findings: Visual Field Loss  Lesion in globe or optic nerve  one blind eye or unilateral blindness  Lesion at optic chiasm  pituitary tumor  Lesion of outer uncrossed fibers at optic chiasm  aneurysm  Lesion R optic tract or R optic radiation * Depending on nature of damage differences in visual field losses will occur Abnormal Findings: Red Eye—Vascular Disorders Conjunctivitis Allergic conjunctivitis Iritis (circumcorneal redness) Primary angle-closure glaucoma (PACG) Subconjunctival hemorrhage Herpes simplex virus (HSV) Abnormal Findings: Cornea and Iris  Pterygium  Corneal abrasion  Normal anterior chamber (for contrast)  Shallow anterior chamber  Hyphema  Hypopyon Abnormal Findings: Opacities in the Lens Central gray opacity—nuclear cataract Abnormal Findings: Opacities in the Lens Star-shaped opacity—cortical cataract Abnormal Findings  Optic disc abnormalities Optic atrophy (disc pallor) Papilledema (choked disc) Excessive cup-disc ratio Abnormal Findings 69  Retinal vessels and background Arteriovenous crossing (Nicking) Narrowed (attenuated) arteries Diabetic retinopathy (DR) Moderate nonproliferative Severe nonproliferative Proliferative