Sensory Disorders - Week 11

MedSurg

The Four Eye Functions That Provide Clear Images and Vision Are

Refraction:

• bends light rays from the outside into the eye through curved surfaces and refractive media and finally to the retina

Pupillary Constriction:

• constriction and dilation control the amount of light that enters the eye

Accommodation:

• allows the healthy eye to focus images sharply on the retina whether the image is close to the eye or distant

Convergence:

• the ability to turn both eyes inward toward the nose at the same time

Coordinated Eye Movements ensure that Both Eyes receive an image at the same time so only a single image is seen:

• the muscles around the eye are innervated by cranial nerves III (oculomotor), IV (trochlear), and VI (abducens)

• the optic nerve (II) is the nerve of sight, connecting the optic disc to the brain

• the trigeminal nerve (V) stimulates the blink reflex when the cornea is touched

• the facial nerve (VII) innervates the lacrimal glands and muscles for lid closure

Assessment of the Six Cardinal Fields

To assess muscle function of the eyes

• the eye will not turn to a particular position if the muscle is weak or if the controlling nerve is affected

Vision Testing

Visual acuity tests measure both distance (snellen) and near vision (rosenbaum pocket vision screener)

• record findings as a comparison between what the patient can read at 20 feet and the distance that a person with a normal vision can read at the same line

  • 20/50 means that the patient sees at 20 feet from the chart what a healthy eye sees at 50 feet

  • a patient reads all five letters from the 20/20 line on the snellen chart with the right eye (OD) and three of the five letters on the 20/30 line with the left eye (OS): the visual acuity is OD: 20/20 and OS: 20/30

Age-Related Changes: Arcus Senilis

An opaque, blueish white ring within the outer edge of the cornea caused by fat deposits

Age-Related Changes: Presbyopia

Near objects (like reading material) must be placed further from the eye to be seen clearly

Age-Related Changes: Ectropion

The lower eyelid may relax and fall away from the eye, leading to dry eye manifestations

Age-Related Changes: Other

Structural changes occur with aging

• decreased eye muscle tone reducing the ability to keep the gaze focused on a single object

The clarity and shape of the cornea change with age

• cornea flattens, and the curve of its surface becomes irregular, worsening or causing astigmatisms’s and blurs the vision

With age, the iris has less ability to dilate, which leads to difficulty in adapting to dark environments

Refraction

Bending of light rays for the ability of the eye to focus images on the retina and depends on the length of the eye from front to back and the refractive power of the lens system

• problems in either eye length or refraction can result in refractive errors

  • examples:

    • emmetropia

    • hyperopia

    • myopia

    • astigmatism

Emmetropia

Perfect refraction of the eye in which light rays from a distant source are focused into a sharp image on the retina

• presbyopia: age-related issue in which the lens loses its elasticity and is less able to change shape to focus the eye for close work

  • as a result images fall behind the retina (hyperopia) and this usually beings in peoples 40s

Hyperopia (Farrsightedness)

Occurs when the eye does not refract light enough, as a result, images actually converge behind the retina

Signs:

• distant vision NORMAL, near vision POOR

Treatment:

• corrected with a convex lens in eyeglasses or contact lenses

Myopia (Nearsightedness)

Occurs when the eye over bends the light and images converge in front of the retina

Signs:

• near vision is NORMAL, distance vision is POOR

Treatment:

• corrected with a BICONCAVE lens in eyeglasses or contact lenses

Astigmatism

Refractive error caused by unevenly curved surfaces on or in the eye, especially of the cornea. These uneven surfaces distort vision.

• because the light rays are not refracted equally in all directions, the image does not focus on the retina

Nursing Interventions for Refractive Errors

Eyeglasses and/or contact lenses

Laser in-situ keratomileusis (LASKI) surgery or photo-refractive keratectomy (PRK)

• both of these procedures can correct nearsightedness, farsightedness and astigmatism

• powerful laser pulses reshape the deeper corneal layers

Blindness

Having best corrected visual acuity that can range from 20/400 to no light perception. Legally defined by visual acuity with corrective lenses is 20/200 or less in the better eye or if the visual field is 20 degrees or less

• blindness can occur in one or both eyes

Nursing Interventions for Blindness

Communication

Safety

Ambulation

Self-care

Support

Glaucoma

Group of eye disorders resulting in increased IOP

• a normal IOP requires a balance between production and outflow of aqueous humor

  • too high: the extra pressure compresses the retinal blood vessels and photoreceptors and their synapsing nerve fibers

    • this compression results in poorly oxygenated photoreceptors and nerve fibers resulting in these sensitive nerve tissues to become ischemic and die (when too many have died, vision is lost permanently)

• tissue damage starts in the periphery and moves inward toward the fovea centralis

Normal IOP

When the aqueous fluid production and drainage are in balance, the IOP is 10-21 mmHg

Primary Open-Angle Glaucoma (POAG) or Wide Angle Glaucoma

Most common form of primary glaucoma where the outflow of aqueous humor through the chamber angle is reduced

• this can affect both eyes and has no manifestations in the early stages

Primary Angle-Closure Glaucoma (PACG) or Acute/Narrow-Angle Glaucoma

Forward displacement of the iris, which presses against the cornea and closes the chamber angle, suddenly preventing outflow of the aqueous humor

• sudden onset and is an emergency!

Signs of PACG

Severe pain in the eye or forehead

Redness

Headache

Decreased/blurred vision

Seeing halos/rainbows

Nausea/vomiting

Signs of POAG

Early on there is no pain or manifestations. eventually patients will present with loss of peripheral vision and halos

Nursing Interventions/Pharmacology for Glaucoma

Prostaglandin Agonists

• drugs reduce IOPy increased aqueous humor outflow

Adrenergic Agonists/Beta-Adrenergic Blockers

• reduce IOP by limiting the production of aqueous humor and by dilating the pupil

Cholinergic Agonists

• reduce IOP by increasing the outflow of aqueous humor

Carbonic Anhydrase

• inhibitors directly and strongly inhibit production of aqueous humor

Systemic Osmotic’s

• may be given for PACG to rapidly reduce IOP

  • oral glycerin and IV mannitol

• Surgery is an option

Cataracts

Lens opacity that distorts the image

• both eyes may have this but the rate of progression in each eye is different

Signs of Cataracts

Early:

• slightly blurred vision

• decrease color perception

Blurred vision, double vision, and opacity

Cataract Nursing Interventions

Prevention through

• smoking cessation

• weight reduction

• optimal blood sugar control

• wearing sunglasses

Promote safety and independence

Surgery when symptoms interfere with ADLs

Post Surgery:

• educate on the importance of close adherence to eye drop regimen after surgery

• wear a light eye patch at night to prevent accidental rubbing

• assess for signs of infection

• remind the patient to avoid activities that might increase IOP

Macular Degeneration

Deterioration of the macula (area of central vision) with the most common being the age-related macular degeneration (AMD)

Dry AMD

Most common

• caused by gradual blockage of retinal capillaries, allowing retinal cells in the macula to become ischemic and necrotic

Wet AMD

Growth of new blood vessels in the macula, which have thin walls and leak blood and fluid

Macular Degeneration Signs

Central vision declines

Mild blurring

Distortion

Eventual loss of all central vision

Macular Degeneration Nursing Interventions

Prevention is key to slow the progression of vision loss!

• dietary intake of antioxidants, vitamin B12, vitamin E, and the carotenoids

• control HTN and stop smoking

Supportive care

Wet AMD:

• laser therapy to seal the leaking blood vessels can limit the extent of the damage

• ocular injections with the vascular endothelial growth factor inhibitors (VEGFIs) such as becacizumab (avastin) or ranibizumab (lucentis)

Retinal Tear

More jagged and irregular shaped break in the retina

Retinal Detachement

The separation of the retina from the epithelium classified by the type and cause of their development

Signs of Retinal Detachment

Sudden onset

Painless

Bright flashes of light (photopsia)

Floating dark spots (floaters)

Shade or curtain coming across the vision

Nursing Interventions for Retinal Disorders

Education and supportive care

Retinal hole/tear: defect may be closed or sealed with surgery

Retinal detachment: surgical repair via scleral buckling, to place the retina in contact with the underlying structures

Keratoconjunctivits Sicca or Dry Eye Syndrome

Results from changes in tear production, tear composition or tear distribution

• the patient may have a foreign body sensation in the eye, burning and itching in the eyes and photophobia

• corneal light reflex is dulled

Keratoconjunctivits Sicca or Dry Eye Syndrome Treatment

Artificial Tears (HypoTears, Refresh)

• can be used to reduce daytime dryness

Lubricating Ointment at Night

• Lacri-Lube SOP, Refresh P.M.

Cyclosporine (Restasis)

• these eyedrops may be prescribed to increase tear production once daily

Surgery

Conjunctivitis

Inflammation with or without infection of the conjunctiva, inflammation usually occurs from exposure to allergens or irritants

• called pink eye often and is common in children

Signs of Conjunctivitis

A gritty feeling in one or both eyes

Itching/burning sensation in one or both eyes

Excessive tearing

Discharge from one or both eyes

Swollen eyelids

Pink discoloration to the whites of one or both eyes

Increased sensitivity to light

Allergic Conjunctivitis

Occurs commonly in people who already have seasonal allergies, these symptoms will develop when they come into contact with a substance that triggers an allergic reaction in their eyes

Signs:

• edema

• sensation of burning

• bloodshot eye appearance

• excessive tears/watery drainage

• extreme itching

• severe photophobia

Treatment:

• cool compresses and artificial tears sometimes relieve discomfort in mild cases

• NSAIDs, antihistamines

• vasoconstrictor and corticosteroid eye drops

• instruct patients to avoid using makeup near the eye until all symptoms are gone

Viral Conjunctivitis

Most commonly caused by contagious viruses associated with the common cold

• since tears drain into the nasal passageway, forceful nose blowing can cause a virus to move from your respiratory system to your eyes

Signs:

• tearing, drainage, itchiness, redness, and light sensitivity

• recent or current upper respiratory infection

• possibly pre-auricular lymphadenopathy

Treatment:

• symptoms can often be relieved with cool compresses or artificial tear solutions

• topical steroid drops may be prescribed to reduce the discomfort from inflammation in severe cases

Bacterial Conjunctivitis

An infection most often caused by staphylococcal or streptococcal bacteria from your own skin or respiratory system

Signs:

• blood vessel dilation, redness, edema, burning, discharge

  • discharge is watery at first then becomes thicker with shreds of mucus (will have crusting in the morning)

Treatment:

• cultures of the drainage may be obtained to identify the organism

• ophthalmic antibiotics are prescribed to eliminate the infection

• teach the patient the importance of preventing the spread of the infection to the other eye or to other people

Corneal Abrasion

Scrape or scratch injury of the cornea (painful condition) - typically caused by a small foreign body, trauma, contact lens use

Signs:

• significant discomfort

• red eyes

• reduced vision

• tearing

• hypersensitive to light

Corneal Ulceration

Deeper injury (open sore/erosion from inflammation or infection) that goes through the bowman’s layer into the deeper layers of the cornea

• this is an emergency, the cornea has no separate blood supply and infections that can permanently impair vision develop rapidly

Complications of Corneal Ulcerations can include:

Scarring

Erosion into the eye leading to perforation

Loss of vision

Nursing Interventions for Corneal Disorders

Corneal abrasions usually heal within several days with no loss of vision

Antibiotic eye drops are usually prescribed for both corneal abrasions and corneal ulcers

NO topical anesthetic eye drops

Possibly use a pressure patch to immobilize the eyelids

Severe corneal ulcers may require hospitalization and IV antibiotics

Surgery and a corneal transplant

Trauma: Foreign Bodies

Eyelashes, dust, dirt, and/or airborne particles that come in contact with the conjunctiva or cornea and irritate or abrade the surface

• if nothing is seen on the cornea or conjunctiva, the eyelid is everted to examine the conjunctivae

Signs:

• feeling something is behind the eye

• blurred vision

• pain occurring if the corneal surface is injured

• tearing

• photophobia

Treatment:

• same as corneal abrasions

Trauma: Lacerations

Caused by sharp objects and projectiles occurs most commonly to the eyelids and cornea

• medical attention is needed right away because eye contents may prolapse through the laceration

Signs:

• severe eye pain

• photophobia

• tearing

• decreased vision

• inability to open the eyelid

Treatment:

• initially the eye is closed and a small eye pack is applied to decrease bleeding

• minor lacerations of the eyelid can be sutured in an ED, urgent care, or even an ophthalmologist’s office

Trauma: Penetrating Injuries

Often leads to permanent loss of visual sensory perception as particles can enter the eye and lodge in or behind the eyeball

• common causes: glass, high speed metal or wood particles, BBs, and bullets

Signs:

• eye pain/tenderness

• reports suddenly feeling something hit their eye

• possible visible wound, proptosis, exophthalmos, swelling, ecchymosis, bleeding

• vision MAY be affected

Treatment:

• do NOT apply a pressure patch to the affected eye, try to protect it with a paper cup

• surgery

Three Divisions in the Ear Important for Hearing:

External ear

Middle ear

Inner ear

Main Function of the Ear

Auditory sensory perception (when sound is delivered through the air to the external ear canal)

• sound waves strike the moveable eardrum (creates vibrations)

• eardrum is connected to the first bony ossicle (allowing sound wave vibrations to be transferred from the eardrum to the malleus, incus and stapes)

• receptors of the cochlea transduce (change) the vibrations into action potentials

  • these action potentials are conducted to the brain as nerve impulses by the cochlear portion of the eighth cranial nerve (auditory) nerve

• these nerve impulses are processed and interpreted as sound by the brain in the auditory complex of the temporal lobe

Age Related Changes

Pinna

• becomes elongated because of loss of subcutaneous tissue and decreased elasticity

Hair

• growth in the canal becomes coarser and longer (esp. in men)

Cerumen

• drier and impacts more easily reducing hearing function

Tympanic Membrane

• loses elasticity and may appear dull and retracted

Hearing acuity decreases

The ability to hear high-frequency sound is lost first

• older adults may have particular problems hearing the f, s, sh and pa sounds

Presbycusis

Hearing loss that occurs with aging

• caused by a degeneration of cochlear nerve cells, loss of elasticity of the basilar membrane, or a decrease blood supply to the inner ear

Assessment and Examination for the Ear

Ask about:

• vertigo

• tinnitus

• medications (some may cause otoxicity)

Exam:

• inspect and palpate

• otoscope (hold the otoscope in your dominant hand and gently pull the pinna up and back with your other hand to straighten the canal)

Cerumen (Earwax)

Most common cause of an impacted canal

• but a canal can also become impacted as a result of foreign bodies that can enter or be placed in the external ear canal such as vegetables, beams, pencil erasers and insects

Signs:

• otalgia (ear pain)

• hearing loss

• itching

• dizziness

Cerumen Impaction Nursing Interventions

Watchful waiting

• may clear spontaneously

Manual irrigation

Manual removal

Ceruminolytics

• oils are a good example

External Otitis

Refers to an inflammation of the external auditory canal and is a painful condition caused when irritating or infective agents come into contact with the skin of the external ear

• occurs more often in hot/humid environments (esp. in the summer, also called swimmers ear since people involved in water sports get it often)

Signs:

• redness/tender to touch or movement

• mild itching

• swelling of the ear canal can lead to temporary hearing loss from obstruction

Nursing Interventions for External Otitis

• Apply hear for 20 minutes 3 times a day

• Teach patients to minimize head movements as it can reduce pain

• Avoid any water sport activity for approximately 7-10 days to allow the canal to heal

Pharmacological:

• topical antibiotic drops

• steroid therapies

• oral/IV antibiotics are used in severe cases

• analgesics

How to Apply Ear Drops

Remove/discard any ear packing → irrigate the ear if the eardrum is intact → place the bottle of ear drops in a bowl of warm water for 5 minutes → tilt the patient’s head and place the drops in the ear → move the head back and forth 5 time → insert a cotton ball into the opening of the ear to act as packing

Otitis Media

An infecting agent in the middle ear causes inflammation of the ear mucosa, leading to swelling and irritation of the ossicles within the middle ear, followed by purulent inflammatory exudate

• pathogens will enter the middle ear after eustachian tube dysfunction caused by obstruction related to upper respiratory infections, inflammation of surrounding structures or allergic reactions

Signs:

• fever, ear pain (otalgia)

• reduced hearing

• tinnitus and/or dizziness

• headache

• nausea/vomiting

Otitis Media Nursing Interventions

Supportive care

• quiet environment, low heat application, reduced head movements

Pharmacological

• antibiotics by mouth analgesics, antipyretics

• surgery an option

Weber: Normal Hearing vs. Conductive vs. Sensorineural

Normal: sound is heard equally in both ears

Conductive: sound is head best in the affected ear with hearing loss

Sensorineural: sound is head best in normal hearing era

Rinne: Normal vs. Conductive vs. Sensorineural

Normal: air conduction is audible longer than bone conduction in bone ears

Conductive: sound is heard as long or longer in affected ear (hearing loss)

Sensorineural: air conduction is audible longer than bone conduction in affected ear

Tinnitus

Ringing or noise perception in the ear (is super common and can occur in one or both ears)

• symptoms are mild ringing to loud roaring in the ears

Contributing factors:

• age

• sclerosis of the ossicles (abnormal bone remodeling in the ear disrupting how sound travels)

• underlying disorders, drugs

• exposure to loud noise

Tinnitus Nursing Interventions

Supportive care

• decreased background noise

• ear mold hearing aids

• support groups

Pharmacological:

• prampexiole (mirapex)

Vertigo

Sense of whirling or turning in space, whether that be the person or the surroundings

Dizziness

Also called lightheadedness, its a disturbed sense of a person’s relationship to space

Signs of Vertigo and Dizziness

Nausea/vomiting

Falling

Nystagmus

Hearing loss

Tinnitus

Vertigo and Dizziness Nursing Interventions

Supportive care

• restrict head movement and change positions slowly

Pharmacological

• dimenhydrinate OTC (Dramamine)

• meclizine

• scopolamine

• diazepam

Meniere’s Disease

Abnormality in the inner ear fluid balance caused by malabsorption in the endolymphatic sac or blockage in the endolympathic duct

Three features:

• tinnitus

• one-sided sensorineural auditory sensory perception loss

• vertigo (occurring in attacks that can last for several days)

Meniere’s Disease Nursing Interventions

Supportive care

• move the head slowly to prevent worsening of the vertigo

• nutrition and lifestyle changes can reduce the amount of endolympathic fluid

Pharmacological:

• mild diuretics to relieve symptoms by lowering the pressure in the ear

• antihistamines to shorten the attacks

• benzodiazepines in acute instances to help control vertigo

• antiemetics to control N/V

Surgery

Hearing Loss

Deafness is partial or complete loss of the ability to hear

Signs:

• tinnitus

• increasing inability to hear when in a group

• a need to turn up the volume of the television

• can trigger changes in attitude

• inability to communicate

• unawareness of surroundings

• the ability to hear high-frequency consonants (esp. s, sh, f, th, and ch, is lost first)

Tests for Hearing Loss

Rinne

• air to bone conduction (place vibrating tuning fork on mastoid then to the front of the ear canal)

Weber

• lateralization (place vibrating tuning fork on the midline of the forehead)

Audiometry

X-ray, CT, MRI

Nursing Interventions for Hearing Loss

Protective measures

• ear muffler, avoiding ototoxic medications

Correct underlying issue

Assistive devices

• portable amplifiers

• hearing aids

• learning lip reading, ASL, and/or brail

Surgery