Visual Impairment

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					         Visual Impairment
       (Glaucoma & Cataract)


Dr. Belal M. Hijji, RN, PhD
May 18 & 21, 2011
                 Learning Outcomes

At the end of this lecture, students will be able to:
• Recognise the causes and effects of visual impairment
   on an individual.
• Define glaucoma and identify its clinical manifestations.
• Identify diagnostic tests for assessment of glaucoma and
   cataract.
• Discuss the medical and nursing management of
   patients with glaucoma and cataract.




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                     Introduction

• Impaired vision affects an individual’s independence in
  self-care, work and lifestyle choices, sense of self-
  esteem, safety, ability to interact with society and the
  environment, and overall quality of life. Many of the
  leading causes of visual impairment and blindness are
  cataracts, glaucoma, macular degeneration, and diabetic
  retinopathy. Younger people are also at risk for eye
  disorders, particularly traumatic injuries.




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                          Glaucoma
• Glaucoma is a group of ocular conditions characterized
  by optic nerve damage which is related to high IOP
  caused by congestion of aqueous humor in the eye.
• Glaucoma is one of the leading causes of irreversible
  blindness in the world. So far, there is no cure for
  glaucoma.
                        Clinical Manifestations
• Most patients are unaware that they have the disease
  until they have experienced visual changes and vision
  loss.
• Patients experiences blurred vision or “halos” around
  lights, difficulty focusing, difficulty adjusting eyes in low
  lighting, loss of peripheral vision, aching or discomfort
  around the eyes, and headache.

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      Assessment and Diagnostic Findings
• The patient’s ocular and medical history must be detailed
  to investigate the history of predisposing factors.
• The major types of examinations are: tonometry to
  measure the IOP, ophthalmoscopy to inspect the optic
  nerve, gonioscopy and perimetry to assess the visual
  fields.
• Changes in the optic nerve significant for diagnosis are
  pallor and cupping of the optic nerve disc. Cupping is
  characterized by exaggerated bending of the blood
  vessels as they cross the optic disc, resulting in an
  enlarged optic cup that appears more basinlike compared
  with a normal cup.
• As the optic nerve damage increases, visual perception in
  the area is lost.

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6
Gonioscopy describes the use of a gonioscope in conjunction with a
slit lamp or operating microscope to gain a view of the iridocorneal
angle, or the anatomical angle formed between the eye's cornea and
iris.
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                 Medical Management

• Treatment aims at preventing optic nerve damage
  through medical therapy, laser or non-laser surgery, or a
  combination.
• Lifelong therapy is indicated as glaucoma is not curable.
  Optic nerve damage is irreversible. However, further
  damage can be controlled by maintaining an IOP within
  an acceptable range (10-21 mmHg).
• The initial target for IOP reduction is typically set at 30%
  lower than the current pressure. If there is evidence of
  progressive damage, the target IOP is again lowered
  until the optic nerve shows stability.




                                                             9
              Pharmacologic Therapy
• The IOP lowering systemic and topical medications.
• The patient is usually started on the lowest dose of
  topical medication (beta-blockers) and then advanced to
  increased concentrations until the desired IOP level is
  reached and maintained.
• One eye is treated first, with the other eye used as a
  control; once efficacy has been established, treatment of
  the fellow eye is started.
• If the IOP is elevated in both eyes, both are treated.
• When results are not satisfactory, a new medication is
  substituted.
• The main markers of the efficacy of the medication in
  glaucoma control are lowering of the IOP to the target
  pressure, appearance of the optic nerve head, and the
  visual field.
                                                          10
• Several types of ocular medications are used to treat
  glaucoma by decreasing aqueous humor production and/
  or increasing aqueous fluid outflow between the iris and
  lens. These include alpha adrenergic agonists
  (apraclonidine), beta-blockers (timolol), adrenergic
  agonists (epinephrine), miotics (pilocarpine), carbonic
  anhydrase inhibitors (acetazolamide), and
  prostaglandins (latanoprost). All these medications
  (except pilocarpine) reduce aqueous humor production.
  Pilocarpine increases aqueous fluid outflow causing
  miosis (constriction of the pupil).



                                                        11
                Surgical Management
• In laser trabeculoplasty for glaucoma, laser burns
  promote outflow of aqueous humor and decreasing IOP.
• The procedure is indicated when IOP is inadequately
  controlled by medications.
• A serious complication of this procedure is a transient
  rise in IOP (usually 2 hours after surgery) that may
  become persistent. IOP assessment in the immediate
  postoperative period is essential.
• In laser iridotomy for pupillary block glaucoma, an
  opening is made in the iris to eliminate the pupillary
  block.
• Potential complications are burns to the cornea, lens, or
  retina; transient elevated IOP; closure of the iridotomy;
  uveitis (iritis); and blurring. Pilocarpine is usually
  prescribed to prevent closure of the iridotomy.
                                                          12
                 Nursing Management

• Teaching patients about glaucoma care
   – The lifelong therapeutic regimen mandates patient
     education.
   – Nurses should stress the importance of strict adherence to
     the medication regimen.
   – Nurses encountering patients with glaucoma as a
     secondary diagnosis should assess their level of
     knowledge and compliance with the therapeutic regimen.




                                                              13
• Continuing glaucoma care at home
   – For patients with severe glaucoma, referral to services that
     assist the patient in performing customary activities may
     be needed.
   – The loss of peripheral vision impairs mobility the most.
     These patients need to be referred to low vision and
     rehabilitation services.
   – Reassurance and emotional support are important aspects
     of care.
   – The family must be integrated into the plan of care, and
     family members should be encouraged to screen for
     glaucoma.




                                                               14
                        Cataracts

• A cataract is a lens opacity or cloudiness that can affect
  one or both eyes.
• According to the World Health Organization, cataract is
  the leading cause of blindness in the world.




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.




    16
                     Pathophysiology
• Cataracts can develop at any age for a variety of causes
  including aging, retinal surgery, infections, corticosteroids,
  smoking, poor nutrition, obesity, dehydration, trauma, and
  DM.
• The nuclear, cortical, and posterior subcapsular cataracts
  are the most common types and are defined by their
  location in the lens.
• A nuclear cataract is associated with myopia (defective
  vision of distant objects), which worsens when the cataract
  progresses. Dense cataract severely blurs [‫]يغشى البصر‬
  vision.
• A cortical cataract involves the anterior, posterior, or the
  periphery of the cortex of the lens. Vision is worse in very
  bright light.
• Posterior subcapsular cataracts occur in front of the
  posterior capsule. In some cases, it is associated with
  prolonged corticosteroid use, inflammation, or trauma.
  Near vision is diminished, and the eye is increasingly
                                                               17
  sensitive to glare [‫ ]ساطع‬from bright light.
               Clinical Manifestations

• Painless, blurry vision is characteristic of cataracts.
• Light scattering is common, and the individual
  experiences reduced contrast sensitivity, sensitivity to
  glare, and reduced visual acuity, dimmer surroundings
  (as if glasses need cleaning), diplopia, and brunescens
  (color values shift to yellow-brown).




                                                             18
Contrast is the difference in visual properties that makes an object
distinguishable from other objects and the background. In visual perception
of the real world, contrast is determined by the difference in the colour and
brightness of the object and other objects within the same field of view.


                                                                                19
      Assessment and Diagnostic Findings
• Decreased visual acuity is directly proportionate to
  cataract density.
• The Snellen visual acuity test, ophthalmoscopy, and
  slitlamp biomicroscopic examination are used to
  establish the degree of cataract formation.
• The degree of lens opacity does not always correlate
  with the patient’s functional status.
• Some patients can perform normal activities despite
  clinically significant cataracts. Others with less lens
  opacification have a disproportionate decrease in visual
  acuity; hence, visual acuity is an imperfect measure of
  visual impairment.

                                                             20
                Medical Management
• No nonsurgical treatment cures cataracts.
• In the early stages of cataract development, glasses,
  contact lenses, strong bifocals [‫ ,]النظارة ثنائية البؤرة‬or
  magnifying lenses may improve vision.
• Reducing glare with proper light and appropriate lighting
  can facilitate reading. Mydriatics (atropine) can be used
  as short-term treatment to dilate the pupil and allow
  more light to reach the retina.
• Intracapsular cataract extraction. The entire lens (ie,
  nucleus, cortex, and capsule) is removed, and fine
  sutures close the incision. ICCE is infrequently used; it is
  indicated when there is a need to remove the entire lens,
  such as with a subluxated cataract (ie, partially or
  completely dislocated lens).



                                                            21
• Extracapsular surgery. Extracapsular cataract extraction
  (ECCE) achieves the intactness of smaller incisional
  wounds (less trauma to the eye) and maintenance of the
  posterior capsule of the lens, reducing postoperative
  complications, particularly retinal. In ECCE, a portion of
  the anterior capsule is removed, allowing extraction of
  the lens nucleus and cortex.
• Lens replacement. After removal of the crystalline lens
  which focuses light on the retina, it must be replaced for
  the patient to see clearly.




                                                           22
                Nursing Management
• Providing preoperative care
   – To reduce the risk for retrobulbar hemorrhage,
     anticoagulation therapy is withheld, if medically
     appropriate. Aspirin should be withheld for 5 to 7
     days, nonsteroidal anti-inflammatory medications
     (NSAIDs) for 3 to 5 days, and warfarin (Coumadin)
     until the prothrombin time of 1.5 is almost reached.
   – Dilating drops are administered every 10 minutes for
     four doses at least 1 hour before surgery. Additional
     dilating drops may be administered in the operating
     room (immediately before surgery) if the affected eye
     is not fully dilated. Prophylactic antibiotic,
     corticosteroid, and NSAID drops may be used.

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• Providing postoperative care
   – The nurse provides the patient with verbal and written
     instruction regarding how to protect the eye,
     administer medications, recognize signs of
     complications, and obtain emergency care.
   – The nurse instructs the patient regarding home care
     (Chart 58-6, page 1764)
   – The nurse also explains that there is minimal
     discomfort after surgery and instructs the patient to
     take a mild analgesic agent PRN. Antibiotic, anti-
     inflammatory, and corticosteroid eye drops or
     ointments are prescribed postoperatively.




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