NCLEX RN GUIDE                                                                                   the best of NCLEX

Neurological 8

akinetic mutism
CT scan
decorticate posture
homonymous hemianopia
nuchal rigidity
prodromal period
transient ischemic attack

  1. Senses: Eye and Ear
    1. Eye structures
      1. Three layers of the eye: sclera, choroid, and retina
        1. Sclera: maintains eye shape
        2. Choroid: packed with blood vessels and pigmented to absorb light and prevent blurring of image;
          1. choroid forms irisand lensin front.
          2. Schlemm's canal(venous sinus) circles where cornea and iris meet; iris gives eye its color
          3. muscles of iris adjust pupil
          4. pupil adjusts to:
            1. protect retina
            2. allow enough light to stimulate retina
            3. improve depth perception
            4. respond to sympathetic nervous system with dilation
          5. ciliary body(smooth muscle) contracts to reduce tension of suspensory ligamenton lens
          6. lens converges light onto retina
        1. Retina: inner, posterior layer that is photosensitive (illustration)
          1. consists of four layers
            1. pigmented epithelial cell
            2. photoreceptor cells (rodsand cones)
            3. bipolar neuron
            4. ganglion neuron
          2. optic disk: retinal area of optic disk contains no photoreceptors (blind spot)
          3. photoreceptor cells: turn light into nerve impulses to optic nerve, cranial nerve II
            1. rods: located more peripherally - around edges of retina
              • black, white, gray vision
              • peripheral vision
            2. cones: located in fovea centralis
              • three types: red, green, and blue receptors
              • fine discrimination and color vision
    2. Optic nerve, cranial nerve II
      1. Nerve fibers from medianhalf of each retina cross at chiasmand travel to opposite sides of the brain
      2. Nerve fibers from lateralhalves of retina remain uncrossed
    3. Chambers
      1. Anterior chamber (locus of intraocular pressure [IOP]) and
      2. Posterior chamber 
    4. Vitreous body
    5. Lens
      1. Separates the posterior chamber from the vitreous body
      2. Transparent
      3. Held in position by suspensory ligaments attached to the ciliary body
    6. Accessory structures
      1. Protective structures: socket, eyelid, eyelashes, eyebrow, conjunctiva
      2. Lacrimal: secretes and drains fluid that moistens and lubricates the front surface of the eye (illustration); with decreased blinking less secretions with complaints of "dry" or maybe "itchy" eyes
      3. Six oculomotormuscles surround and enter the eyeball (illustration)
  2. Eye Functions
    1. Light reception
      1. Light passes through the cornea, aqueous humor, lens, and vitreous body to retina
      2. The density of the cornea slows the light, and the curvature of the cornea bends it (refraction)
      3. The lens further bends and redirects the light to a point on the retina
      4. At this point, light stimulates photoreceptor cells (rods, cones) which transmit electrical impulses
      5. These impulses travel through the optic nerve to the brain
    2. Accommodation - decreases with aging
      1. Process by which the lens changes shape to view an object at close range (or long range)
      2. Proper vision requires three processes:
        1. convergence: image of object falls exactly on fovea centralis retinaeof both eyes
        2. focusing of the lens (ciliary body [ciliary muscles] contract or relax)
        3. constriction or relaxation of pupils to regulate light and clarify image on retina
      3. When muscles that carry out these three processes are weak or paralyzed, result is strabismus
    3. Binocular vision
      1. Allows brain to judge distance
      2. Brain judges
        1. difference between two images
        2. the amount of retina taken up by the image
        3. difference between familiar and unfamiliar objects (example: person standing next to an elephant)
        4. different shades of color
      3. Both eyes must move together for clear focus (called conjugate eye movements); thus, to immobilize one eye, both must be covered
  3. Disorders of the Eye

Overview: eye disorders from front to back of eye

Eye disorders from most common to least common

    1. Disorders of refraction
      1. Myopia(near-sightedness) - blurred distance vision, but clear close vision
      2. Hyperopia (far-sightedness) - blurred close vision, but clear distant vision
      3. Presbyopia - in middle age, lens loses elasticity with results of hyperopia
      4. Astigmatism- lens refracts light rays to focus on two different points of retina
    2. Glaucoma - second most common cause of vision loss in the USA (illustration); may be unilateral or bilateral
      1. Most common type: chronic open-angle glaucoma (simple, adult primary, primary open-angle)
        1. etiology/epidemiology
          1. hereditary link
          2. etiology unknown
          3. aqueous humordoes not drain adequately which leads to increased intraocular pressure (IOP)
          4. this pressure on optic nerve causes destruction of nerve fibers in retina to result in a vision loss
        2. findings
          1. most clients are without findings until a loss of vision
          2. peripheral vision affected first
          3. three classic assessment findings

        1. management
          1. expected outcomes
            • reduction of IOP
            • prevention of visual field defects
          2. treatment of choice: pharmacotherapy
            • miotic eyedrops (parasympathomimetic agents)
            • carbonic anhydrase inhibitors - Diamox
            • beta-adrenergic blocking agents- Timoptic drops
            • epinephrine eyedrops (contraindicated in clients with cardiac conditions) - more in emergency care
          3. trabeculectomy or laser trabeculectomy
            • performed when pharmacological agents not effective
            • small piece of sclera containing the trabecular network is removed and an iridectomyis performed
            • cycloplegicand steroids are instilled
            • antibiotics may be ordered
            • a mydriaticis then used to prevent adhesions to the cornea
        1. nursing interventions
          1. for pharmacotherapy management
            • compliance with medical treatment
            • teach client to instill eyedrops usually recommended before bedtime
            • teach safety risks related to impaired vision
          2. for trabeculectomy by traditional surgery
            • monitor dressing for excessive bleeding
            • antiemetics, analgesics and antibiotics as ordered
            • mydriatics as ordered.
            • assist client with activities of daily living
          3. for trabeculectomy by laser surgery
            • vision may be blurred for first day or two post-op
            • eye patch or sunglasses for photophobia
            • analgesics as ordered
          4. education of client with glaucoma
            • avoid activities that increase IOP - bending, stooping, straining, caughing, blowing nose
            • stress importance of routine eye examinations - usually yearly