Overview Anatomy

8/8/2019 Overview Anatomy

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Overview Anatomy & Physiology of the Eye

External Structure of Eye

a. Eyelids (Palpebrae) & Eyelashes: protect the eye from foreign particlesb. Conjunctiva:

Palpebral Conjunctiva: pink; lines inner surface of eyelids Bulbar Conjunctiva: white with small blood vessels, covers anterior sclera

c. Lacrimal Apparatus(lacrimal gland & its ducts & passage): produces tears to lubricate the eye & moistenthe cornea; tears drain into the nasolacrimal duct, which empties into nasal cavity

d. The movement of the eye is controlled by6 extraocular muscles(EOM)

Internal Structure of Eye

A. 3 layers of the eyeball1. Outer Layer

a. Sclera: tough, white connective tissue (white of the eye);located anteriorly & posteriorlyb. Cornea: transparent tissue through which light enters the eye; located anteriorly

2. Middle Layera. Choroid: highly vascular layer, nourishes retina; located posteriorlyb. Ciliary Body: anterior to choroid, secrets aqueous humor; muscle change shape of lensc. Iris: pigmented membrane behind cornea, gives color to eye; located anteriorlyd. Pupil: is circular opening in the middle of the iris that constrict or dilates to regulate amount of light

entering the eye

3. Inner Layera. Light-sensitive layer composed of rods & cones(visual cell)

Cones: specialized for fine discrimination & color vision; (daylight / colored vision) Rods: more sensitive to light than cones, aid in peripheral vision; (night twilight vision)

b. Optic Disk: area in retina for entrance of optic nerve, has no photoreceptors

B. Lens: transparent body that focuses image on retinaC. Fluid of the eye

1. Aqueous Humor: clear, watery fluid in anterior & posterior chambers in anterior part of eye; serves asrefracting medium & provides nutrients to lens & cornea; contribute to maintenance of intraocular

pressure

2. Vitreous Humor: clear, gelatinous material that fills posterior cavity of eye; maintains transparency &form of eye

Visual Pathways

a. Retina (rods & cones) translates light waves into neural impulses that travel over the optic nervesb. Optic nerves for each eye meet at the optic chiasm

Fibers from median halves of the retinas cross here & travel to the opposite side of the brain Fibers from lateral halves of retinas remain uncrossed


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c. Optic nerves continue from optic chiasm as optic tracts & travels to the cerebrum(occipital lobe) wherevisual impulses are perceived & interpreted

Canal of schlemm: site of aqueous humor drainage

Meibomian gland: secrets a lubricating fluid inside the eyelid

Maculla lutea: yellow spot center of retina

Fovea centralis: area with highest visual acuity or acute vision

2 muscles of iris:

Circular smooth muscle fiber: Constricts the pupil

Radial smooth muscle fiber: Dilates the pupil

Physiology of vision

4 Physiological processes for vision to occur:

1. Refraction of light rays: bending of light rays2. Accommodation of lens3. Constriction & dilation of pupils4. Convergence of eyes

Unit of measurements of refraction:diopters

Normal eye refraction:emmetropia

Normal IOP: 12-21 mmHg

Error ofRefraction

1. Myopia:nearsightedness:Treatment:biconcave lens2. Hyperopia:farsightedness:Treatment:biconvex lens3. Astigmatisim:distorted vision:Treatment:cylindrical4. Presbyopia:old sight inelasticity of lens due to aging: Treatment:bifocal lens or double vista

Accommodation of lenses: based on thelmholtz theory of accommodation

Near Vision:Ciliary muscle contracts: Lens bulges

Far Vision:ciliary muscle dilates / relaxes:lens is flat

Convergence of the eye:

Error:

1. Exotropia:1 eye normal2. Esophoria: corrected by corrective eye surgery3. Strabismus: squint eye4. Amblyopia: prolong squinting


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Common Visual Disorder

Glaucoma

Characterized by increase intraocular pressure resulting in progressive loss of vision May cause blindness if not recognized & treated Early detection is very important preventable but not curable Regular eye exam including tonometry for person over age 40 is recommended

Predisposing Factors

1. Common among 40 years old and above2. Hereditary3. Hypertension4. Obesity5.

History of previous eye surgery, trauma, inflammation

Types of Glaucoma:

1. Chronic (open-angle) Glaucoma: Most common form Due to obstruction of the outflow of aqueous humor, in trabecular meshwork or canal of schlemm

2. Acute(close-angle)Glaucoma: Due to forward displacement of the iris against the cornea, obstructing the outflow of the aqueous

humor

Occurs suddenly & is an emergency situation If untreated it will result to blindness

3. Chronic (close-angle)Glaucoma: similar to acute (close-angle) glaucoma, with the potential for an acute attack

S/sx

1. Chronic (open-angle)Glaucoma:symptoms develops slowly Impaired peripheral vision (PS: tunnel vision) Halos around light Mild discomfort in the eye Loss of central vision if unarrested

2. Acute(close-angle)Glaucoma Severe eye pain Blurred cloudy vision Halos around light N/V


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Steamy cornea Moderate pupillary dilation

3. Chronic(close-angle)Glaucoma Transient blurred vision Slight eye pain Halos around lights

Dx

1. Visual Acuity: reduced2. Tonometry: reading of 24-32 mmHg suggest glaucoma; may be 50 mmHg of more in acute (close-angle)

glaucoma

3. Ophthalmoscopic exam: reveals narrowing of small vessels of optic disk, cupping of optic disk4. Perimetry: reveals defects in visual field5. Gonioscopy: examine angle of anterior chamber

Medical Management

1. Chronic(open-angle)Glaucomaa. Drug Therapy: one or a combination of the following

Miotics eye drops(Pilocarpine): to increase outflow of aqueous humor Epinephrine eye drops: to decrease aqueous humor production & increase outflow Carbonic Anhydrase Inhibitor: Acetazolamide (Diamox): to decrease aqueous humor production Timolol Maleate (Timoptic):topical beta-adrenergic blocker: to decrease intraocular pressure (IOP)

b. Surgery(if no improvement with drug) Filtering procedure (Trabeculectomy / Trephining): to create artificial openings for the outflow of

aqueous humor

Laser Trabeculoplasty: non-invasive procedure performed with argon laser that can be done on anout-client basis; procedure similar result as trabeculectomy

2. Acute(close-angle)Glaucomaa. Drug Therapy: before surgery

Miotics eye drops (Pilocarpine): to cause pupil to contract & draw iris away from cornea Osmotic Agent(Glycerin oral, Mannitol IV): to decrease intraocular pressure (IOP) Narcotic Analgesic: for pain

b. Surgery Peripheral Iridectomy: portion of the iris is excised to facilitate outflow of aqueous humor Argon Laser Beam Surgery: non-invasive procedure using laser produces same effect as

iridectomy; done in out-client basis

Iridectomy: usually performed on second eye later since a large number of client have an acuteacute attack in the other eye

3. Chronic (close-angle) Glaucomaa. Drug Therapy:


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miotics(pilocarpine)b. Surgery:

bilateral peripheral iridectomy: to prevent acute attacks

Nursing Intervention

1. Administer medication as ordered2. Provide quite, dark environment3. Maintain accurate I & O with the use of osmotic agent4. Prepare client for surgery if indicated5. Provide post-op care6. Provide client teaching & discharge planning

a. Self-administration of eye dropsb. Need to avoid stooping, heavy lifting or pushing, emotional upsets, excessive fluid intake, constrictive

clothing around the neck

c. Need to avoid the use antihistamines or sympathomimetic drugs(found in cold preparation) in close-angle glaucoma since they may cause mydriasis

d. Importance of follow-up caree. Need to wear medic-alert tag

Cataract Decrease opacity of ocular lens Incidence increases with age

Predisposing Factor

1. Aging 65 years and above2. May caused by changes associated with aging (senile cataract)3. Related to congenital4. May develop secondary to trauma, radiation, infection, certain drugs (corticosteroids)5. Diabetes Mellitus6. Prolonged exposure to UV rays

S/sx

1. Loss of central vision2. Blurring or hazy vision3. Progressive decrease of vision4. Glare in bright lights5. Milky white appearance at center of pupils6. Decrease perception to colors

Diagnostic Procedure


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1. Ophthalmoscopic exam: confirms presence of cataract


1. Prepare client for cataract surgery:a. Performed when client can no longer remain independent because of reduced visionb. Surgery performed on one eye at a time; usually in a same day surgery unitc. Local anesthesia & intravenous sedation usually usedd. Types of cataract surgery:

Extracapsular Extraction: lens capsule is excised & the lens is expressed; posterior capsule is left inplace (may be used to support new artificial lens implant); partial removal of lens

Phacoemulsification: type of extracapsular extraction; a hollow needle capable ofultrasonicvibration is inserted into lens, vibrations emulsify the lens, which is aspirated

Intracapsular Extraction: lens is totally removed within its capsules, may be delivered from eye bycryoextraction (lens is frozen with metal probe & removed); total removal of lens & surrounding

capsules

e. Peripheral Iridectomy: may be performed at the time of surgery; small hole cut in iris to preventdevelopment of secondary glaucoma

f. Intraocular Lens Implant: often performed at the time of surgery2. Nursing Intervention Pre-op

a. Assess vision in the unaffected eye since the affected eye will be patched post-opb. Provide pre-op teaching regarding measures to preventintraocular pressure(IOP) post-opc. Administer medication as ordered:

Topical Mydriatics(Mydriacyl) & Cyclopegics(Cyclogyl): to dilate the pupil Topical antibiotics: to prevent infection Acetazolamide(Diamox) & osmotic agent(Oral Glycerin or Mannitol IV):to decreaseintraocular

pressureto provide soft eyeball for surgery

3. Nursing Intervention Post-opa. Reorient the client to surroundingsb. Provide safety measures:

Elevate side rails Provide call bells Assist with ambulation when fully recovered from anesthesia

c. Prevent intraocular pressure & stress on the suture line: Elevate head of the bed 30-40 degree Have the client lie on back or unaffected side Avoid having the client cough, sneeze, bend over, or move head too rapidly Treat nausea with anti-emetics as ordered: to prevent vomiting Give stool softener as ordered: to prevent straining Observe for & report signs of intraocular pressure (IOP):

Severe eye pain


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Restlessness Increased pulse

4. Protect eye from injury:a. Dressing usually removed the day after the surgeryb. Eyeglasses or eye shield used during the dayc. Always use eye shield during the night

5. Administer medication as ordered:a. Topical mydriatics & cycloplegic: to decrease spasm of ciliary body & relieve painb. Topical antibiotics & corticosteroidsc. Mild analgesic as needed

6. Provide client teaching & discharge planning concerning:a. Technique of eyedrop administrationb. Use of eye shield at nightc. No bending, stooping, or liftingd. Report signs & symptoms of complication immediately to physician:

Severe eye pain Decrease vision Excessive drainage Swelling of eyelid

e. Cataract glasses / contact lenses If a lens implant has not been performed the client will need glasses or contact lenses Temporary glasses are worn for 1-4 weeks then permanent glasses fitted Cataract glasses magnify object by 1/3 & distortion peripheral vision

Have the client practice manual coordination with assistance until new spatial relationshipbecomes familiar

Have client practice walking, using stairs, reaching for articles Contact lenses cause less distortion of vision; prescribe at one month

Retinal Detachment

Separation of epithelial surface of retina Detachment or the sensory retina from the pigment epithelium of the retina

Predisposing Factors

1. Trauma2. Aging process3. Severe diabetic retinopathy4. Post-cataract extraction5. Severe myopia (near sightedness)

Pathophysiology


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Tear in the retina allows vitreous humor to seep behind the sensory retina & separate it from the pigmentepithelium

S/sx

1. Curtain veil like vision coming across field of vision2. Flashes of light3. Visual field loss4. Floaters5. Gradual decrease of central vision

Dx

1. Ophthalmoscopic exam: confirms diagnosis

Medical Management

1. Bed rest with eye patched & detached areas dependentto prevent further detachment2. Surgery: necessary to repair detachment

a. Photocoagulation: light beam (argon laser) through dilated pupil creates an inflammatory reaction &scarring to heal the area

b. Cryosurgery or diathermy: application of extreme cold or heat to external globe; inflammatory reactioncauses scarring & healing of area

c. Scleral buckling: shortening of sclera to force pigment epithelium close to retina

Nursing Intervention Pre-op

1. Maintain bed rest as ordered with head of bed flat & detached area in a dependent position2. Use bilateral eye patches as ordered; elevate side rails to prevent injury3. Identify yourself when entering the room4. Orient the client frequently to time of date & surroundings; explain procedures5. Provide diversional activities to provide sensory stimulation

Nursing Intervention Post-op

1. Check orders for positioning & activity level:a. May be on bed rest for 1-2 daysb. May need to position client so that detached area is in dependent position

2. Administer medication as ordered:a. Topical mydriaticsb. Analgesic as needed

3. Provide client teaching & discharge planning concerning:a. Techniques of eyedrop administrationb. Use eye shield at nightc. No bending from waist; no heavy work or lifting for 6 weeksd. Restriction of reading for 3 weeks or more


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e. May watch TVf. Need to check to physician regarding combing & shampooing hair & shavingg. Need to report complications such as recurrence of detachment

Overview of Anatomy & Physiology Of Ear (Hearing)

External Ear

1. Auricle (Pinna): outer projection of ear composed of cartilage & covered by skin; collects sound waves2. External Auditory Canal: lined with skin; glands secretes cerumen (wax), providing protection; transmits

sound waves to tympanic membrane

3. Tympanic Membrane(Eardrum): at end of external canal; vibrates in response to sound & transmitsvibrations to middle ear

Middle Ear

1. Ossiclesa. 3 small bones: malleus(Hammer) attached to tympanic membrane, incus(anvil),stapes (stirrup)b. Ossicles are set in motion by sound waves from tympanic membranec. Sound waves are conducted by vibration to the footplate of the stapes in theoval widow(an opening

between the middle ear & the inner ear)

2. Eustachian Tube: connects nasopharynx & middle ear; bring air into middle ear, thus equalizing pressureon both sides of eardrum

Inner Ear

1. Cochlea Controls hearing Contains Organ of Corti(the true organ of hearing): the receptor end-organ for hearing Transmit sound waves from the oval window & initiates nerve impulses carried by cranial nerve

VIII (acoustic branch) to the brain (temporal lobe of cerebrum)

2. Vestibular Apparatus Organ of balance Composed of three semicircular canals & the utricle

3. Endolymph & Perilymph For static equilibrium

4. Mastoid air cells Air filled spaces in temporal bone in skull

Disorder of the Ear

Otosclerosis

Formation of new spongy bone in the labyrinth of the ear causing fixation of the stapes in the ovalwindow

This prevent transmission of auditory vibration to the inner ear


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Predisposing Factor

1. Found more often in women

Cause

1. Unknown / idiopathic2. There is familial tendency3. Ear trauma & surgery

S/sx

1. Progressive hearing loss2. Tinnitus

Dx

1. Audiometry: reveals conductive hearing loss2. Webers & Rinnes Test: show bone conduction is greater than air conduction

Medical Management

1. Stapedectomy: procedure of choice Removal of diseased portion of stapes & replacement with prosthesis to conduct vibrations from

the middle ear to inner ear

Usually performed under local anesthesia Used to treat otoscrlerosis

Nursing Intervention Pre-op

1. Provide general pre-op nursing care, including an explanation of post-op expectation2. Explain to the client that hearing may improve during surgery & then decrease due to edema & packing

Nursing Intervention Post-op

1. Position the client according to the surgeons orders (possibly with operative ear uppermostto preventdisplacement of the graft)

2. Have the client deep breathe every 2 hours while in bed, but no coughing3. Elevate side rails; assist the client with ambulation & move slowly: may have some vertigo4. Administer medication as ordered:

Analgesic Antibiotics Anti-emetics Anti-motion sickness drug: Meclesine Hcl (Bonamine)

5. Check for dressing frequently for excessive drainage or bleeding6. Assess facial nerve function:Ask the client to do the ff:


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Wrinkle forehead Close eyelids Puff out checks for any asymmetry

7. Question the client about the ff: report existence to physicians Pain Headaches Vertigo Unusual sensations in the ear

8. Provide client teaching & discharge planning concerning:a. Warning against blowing nose or coughing; sneeze with mouth openb. Need to keep ear dry in the shower; no shampooing until allowedc. No flying for 6 mos. Especially if upper respiratory tract infection is presentd. Placement of cotton balls in auditory meatus after packing is removed; change twice daily

Menieres Disease

Disease of the inner ear resulting from dilatation of the endolymphatic system & increase volume ofendolymph

Characterized by recurrent & usually progressive triad of symptoms: vertigo, tinnitus, hearing loss

Predisposing Factor

1. Incidence highest between ages 30 & 60

Cause

2. Unknown / idiopathic3. Theories include the ff:

a. Allergyb. Toxicityc. Localized ischemiad. Hemorrhagee. Viral infectionf. Edema

S/sx

1. Sudden attacks of vertigo lasting hours or days; attacks occurs several times a year2. N/V3. Tinnitus4. Progressive hearing loss5. Nystagmus

Dx


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1. Audiometry: reveals sensorineural hearing loss2. Vestibular Test: reveals decrease function

Medical Management

1. Acute: Atropine(decreases autonomic nervous system activity) Diazepam(Valium) Fentanyl & Droperidol(Innovar)

2. Chronic:a. Drug Therapy:

Vasodilators (nicotinic Acid) Diuretics Mild sedative or tranquilizers: Diazepam(Valium) Antihistamines: Diphenhydramine(Benadryl) Meclizine(antivert)

b. Diet: Low sodium diet Restricted fluid intake Restrict caffeine & nicotine

3. Surgery:a. Surgical destruction of labyrinth causing loss of vestibular & cochlear function (if disease is

unilateral)

b. Intracranial division of vestibular portion of cranial nerve VIIIc. Endolymphatic sac decompression or shuntto equalize pressure in endolymphatic space


1. Maintain bed rest in a quiet, darkened room in position of choice; elevate side rails as needed2. Only move the client for essential care (bath may not be essential)3. Provide emesis basin for vomiting4. Monitor IV Therapy; maintain accurate I&O5. Assist in ambulation when the attack is over6. Administer medication as ordered7. Prepare client for surgery as indicated (pot-op care includes using above measures)8. Provide client care & discharge planning concerning:

a. Use of medication & side effectsb. Low sodium diet & decrease fluid intakec. Importance of eliminating smoking

Overview Anatomy

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