NNN

Sensory Disorders (Eyes, Ears)

Oct 19, 20247 min read1386 words

Also read: Anatomy of the eyes

Anatomy of the Eyes

The eye is made up of various layers:

  1. Outer:
    1. Sclera
    2. Cornea (avasular)
  2. Middle
    1. Uvea
    2. Iris, the pigmented ring of accommodating tissue that controls the amount of light to enter the eyes; these cause pupillary constriction (miosis) in the presence of light, and cause pupillary dilation (medriasis) in the presence of darkness. The examination of the pupil with a penlight to detect these constrictions or dilatations assesses the function of CN III (oculomotor nerve).
      • Drugs that induce miosis are called miotics. Drugs that induce medriasis are called medriatics.
    3. Ciliary Body: the producer of aqueous humor that occupies that fills the eye. This is implicated in glaucoma when overproduction results in an increase in IOP.
    4. Choroid
  3. Inner
    1. Retina: contains retinal vessels and is the sensory unit of the eyes. These function with CN II (optic nerve), assessed with Snellen’s chart (visual acuity).

Cranial Nerve V: The Trigeminal Nerve

The nerve that innervates the cornea via the ophthalmic branch, maxillary branch, and mandibular branch. The reflex tested for the eye is the corneal reflex, which causes the individual to blink when a cotton wisp is used to stimulate the cornea.

Inflammation of the Eyes

  1. Scleritis: inflammation of the sclera
  2. Iritis: inflammation of the iris
  3. Retinitis: inflammation of the retina
  4. Keratitis: inflammation of the cornea, especially after corneal abrasion e.g. due to contact lenses.
  5. Blepharitis: inflammation of the eyelidg

Errors of Refraction

  1. Myopia: near-sightedness, treated with concave lenses.
  2. Hyperopia: far-sightedness, treated with convex lenses.
  3. Astigmatism: irregular curvature of the cornea, treated with cylindrical lenses.
  4. Presbyopia: far-sightedness that occurs with aging.

Ocular Medications

  1. Eye drops: therapeutic fluid administered at the lower conjunctiva.

Close drainage

Place pressure on the area between the corner of the eye and the side of the nose to prevent systemic absorption of the drug (approx. 7% gets absorbed).

  1. Eye ointment

Cataracts

An increase in the opacity of the lens of the eyes. A progressive, painless loss of vision is the main characteristic of cataracts.

  1. Risk Factors: mn. CARDS
    • Corticosteroids
    • Aging
    • Retinal Detachment
    • Diabetes Mellitus, Down Syndrome
    • Smoking
  2. Symptoms
    • Painless blurring of vision
    • White-colored or cloudy lens/pupil
  3. Treatment: cataracts are done primarily through lens removal (phacoemulsification). This may be done with ultrasound vibrations that breaks the lens into fragments. Patients without lens are aphakic (has aphakia). Surgical management is through lens replacement, which uses lens implants or corrective lenses.
  4. Nursing Intervention
    • Post-op: monitor vital signs, level of consciousness, and dressings.
    • Elevate the head of the bed.
    • Lie on the unaffected side.
    • Eyeglasses will be given for the patient when discharged to reduce glare. At night, an eye shield is used to prevent trauma such as scratching.
    • Avoid activities that elevate the IOP: sneezing, coughing, straining or using the valsalva maneuver (utilize a papaya + high residue/fiber diet) to prevent constipation, laxatives may be given. Antiemetics may be given for vomiting patients. Increased IOP may cause hemorrhaging and pain.
    • Priority after surgery: safety. Set siderails.

Glaucoma

Increased IOP (normal: 10 to 21 mmHg) due to an imbalance in the production and drainage of aqueous humor. This results in nerve damage to the optic nerve (CN II).

  1. Signs and Symptoms:
    1. Open Angle Glaucoma: loss of peripheral vision (tunnel vision), where halos are seen when around lights.
    2. Closed Angle Glaucoma: headache and eye pain present due to higher IOP compared to open angle.
  2. Risk Factors
    1. Smoking, Steroids
    2. Aging, Family History, High Myopia
    3. Diabetes Mellitus
  3. Diagnostic Examination
    1. History
    2. Tonometry through a tonometer, which measures IOP
  4. Nursing Intervention
    1. Priority Nursing Diagnosis: risk for injury due to sensory impairment; ensure safety.
    2. Keep lights open to promote pupil constriction. Dark environments allow for dilation, increasing IOP.
    3. Avoid all activities that increase IOP; sneezing, coughing, vomiting, straining, valsalva maneuver
  5. Treatment: decrease production, increase outflow; the main goal is to reduce IOP to prevent CN II damage, which can result in irreversible blindness
    1. Miotics: drugs that constrict the pupil e.g. Pilocarpine and Carbachol. The constriction allows for outflow to be faster, draining the eye.
    2. Topical Beta-Blockers instilled at the lower conjunctiva; betaxolol, timolol. These decrease humor production Always monitor heart rate to check for bradycardia. Trivia: only 7% of eye drops enter systemic circulation.
    3. Diuretics: to reduce pressure by reducing fluid content; acetazolamide (diamox)
    4. Prostaglandin Analogs/Agonist: travoprost, latanoprost; these facilitate humor drainage.
    5. Surgical Management: iridectomy, iridotomy used to facilitate aqueous drainage.

Retinal Detachment

The separation of the choroid from the retina, forming a retinal pigment epithelium (RPE) detached from the sensory layer.

  1. Causes
    1. Diabetic retinopathy
    2. Aphakia
    3. Tumor of the eye
    4. Inflammation of the eye: uvitis (middle layer inflammation)
    5. High myopia
  2. Symptoms:
    1. Flashes of light and sight of floaters (light spots on the foreground of one’s sight)
    2. Sense of a curtain being drawn over the eye.
    3. Painless blurring of vision.
  3. Treatment
    1. Scleral buckle, which promote reattachment of the choroid to the senosry retina.
    2. Pneumatic retinopexy, where the retinal pigment epithelium (RPE) is pushed into the retina via the administration of gas bubbles or silicone oil into the vitreous cavity.
      • Importantly, position the patient PRONE after surgery to position the gas bubble properly in pushing the RPE to the retina.
      • Avoid activities that increases IOP: sneezing, coughing, straining/valsalva, vomiting (use antiemetics), constipation (use high fiber/high residue + papaya diet, or laxatives as ordered)

Ear Disorders

  1. External Ear: ear canal
    • Erythematous ear canal; otitis externa, inflammation of the ear canal.
    • The ear canal is normally skin colored. If inflamed, it is erythematous.
    • Aural tenderness occurs, where manipulation of the pinna, oracle, or canal causes pain.
    • Treatment: analgesics (otic drops)
  2. Middle Ear: tympanic membrane, eustachian tube (connects the ear to the nasopharynx), malleus, indus, stapes (ossicles).
    • Problems with the external or middle ear that results in hearing loss is conductive hearing loss
    • In otitis media, the tympanic membrane bulges and becomes erythematous (normally pearly grey).
    • A consequence of URTIs travelling through the eustachian tube.
  3. Inner Ear: a.k.a. labyrinth; vestibule (semicircular canal), and cochlea
    • Labyrinthitis.
    • Problems with the inner ear or labyrinth that results in hearing loss is sensorineural hearing loss. Often caused by (mn. LMP) labyrinthitis, Meniere’s syndrome, and presbycusis.

Hearing Loss

Hearing loss may be conductive from the affectation of the conducting system of the ears, sensorineural from the affectation of the sensory organ or the nervous system, or functional from psychological or emotional blocking-out of stimulus.

Otitis Externa

Containing the ear canal and other external ear structures, otitis externa is the inflammation of the ear canal. Because it commonly occurs after swimming, it is called “swimmer’s ear”

  1. Symptoms
    1. Erythematous ear canal
    2. Aural Tenderness
  2. Treatment
    1. Antibiotics for infection
    2. Analgesia with otic drugs (ear drops) for pain

Otitis Media

Associated with URTIs (cough or cold). This features a tympanic membrane that bulges and becomes erythematous. Hearing loss associated with this condition is conductive hearing loss. If untreated, this may also cause mastoiditis.

  1. Symptoms
    1. Fever
    2. Ear Pain (Otalgia), a classic symptom of otitis media.
    3. Ear Pressure
    4. Bulging Eardrum
    5. Ear Discharge
  2. Treatment
    1. Antibiotics and analgesia
    2. Tympanotomy or Myringotomy: a surgical perforation of the tympanic membrane used to relieve otalgia by decreasing pressure by facilitate drainage. A repair (tympanoplasty, myringoplasty)

Mastoiditis

A complication of otitis media.

  1. Symptoms: the tympanic membrane is described as (mn. DIRT) dull, immobile, red, and thick.
  2. Treatment: surgery to remove infected mastoid ear cells: mastoidectomy.
    • If unsuccessful in removing infected cells, meningitis, dizziness, and damage to CN 6 (abducens) and 7 (facial).

Otosclerosis

Abnormal bone growth at the level of the stapes, common in pregnant women.

  1. Symptoms
    1. Conductive hearing loss
    2. Normal tympanic membrane (pearly grey)
    3. Often occurs in pregnant patients.
  2. Treatment
    1. Stapedectomy: removal of the stapes and abnormal bone growths.
    2. Application of hearing aids
    3. Sodium fluoride may prevent otosclerosis.

Presbycusis

A form of sensorineural hearing loss related to aging. Hearing is lost due to age because of degenerative changes (atrophy) of the cochlea. Irreversible.

Meniere’s Disease

An inner ear (labyrinth) disorder, where there is an increased fluid (endolymphatic fluid) in the membranous labyrinth. It is primarily idiopathic.

  1. Symptoms
    • Tinnitus, ringing within the ears.
    • Sensorineural Hearing Loss
    • Vertigo (most common and troublesome due to affectation of the cochlea)
  2. Management
    1. Risk for falls or injury due to impaired vestibular function; ensure safety.
    2. Low sodium diet as episodes may be related to high sodium consumption, which further increase fluid volume.
    3. Diuretics to reduce fluid volume if prescribed.
    4. Endolymphatic drainage
    5. Vestibular nerve resection to remove vertigo.
    6. Labyrinthectomy, removal of the inner ear. Permanent deafness.

Backlinks

Graph View