Visual impairment

  • Visual impairment
    • Common problem during childhood
      • In the United States, prevalence of blindness or serious visual impairment is 30 to 64 per 100,000
      • 5% to 10% of all preschoolers
      • Identified through vision screening programs
    • Etiology
      • Prenatal or postnatal infections
      • Retinopathy of prematurity
      • Types of visual impairment
        • Refractive Errors
          • Myopia
            • Nearsightedness: Ability to see objects clearly at close range but not at a distance
            • Pathophysiology
              • Results from eyeball that is too long, causing images to fall in front of the retina
            • Clinical Manifestations
              • Headaches
              • Dizziness
              • Excessive eye rubbing
              • Head tilt or forward head thrusts
              • Difficulty in reading or doing other close work
              • Clumsiness; walking into objects
              • Blinking more than usual or irritability when doing close work
              • Inability to see objects clearly
              • Poor school performance, especially in subjects that require demonstration, such as arithmetic
            • Treatment
              • Corrected with biconcave lenses that focus rays on retina
              • May be corrected with laser surgery
          • Hyperopia
            • Farsightedness: Ability to see objects at a distance but not at close range
            • Pathophysiology
              • Results from eyeball that is too short, causing image to focus beyond retina
            • Clinical Manifestations
              • Because of accommodative ability, child can usually see objects at all ranges
              • Most children are normally hyperopic until about 7 years of age
            • Treatment
              • When required, corrected with convex lenses that focus rays on retina
              • May be corrected with laser surgery
          • Astigmatism
            • Unequal curvatures in refractive apparatus
            • Pathophysiology
              • Results from unequal curvatures in cornea or lens that cause light rays to bend in different directions
            • Clinical Manifestations
              • Depend on severity of refractive error in each eye
              • Possible clinical manifestations of myopia
            • Treatment
              • Corrected with special lenses that compensate for refractive errors
              • May be corrected with laser surgery
          • Anisometropia
            • Different refractive strength in each eye
            • Pathophysiology
              • May develop amblyopia because weaker eye is used less
            • Clinical Manifestations
              • Depend on severity of refractive error in each eye
              • Possible clinical manifestations of myopia
            • Treatment
              • Treated with corrective lenses, preferably contact lenses, to improve vision in each eye so that they work as a unit
              • May be corrected with laser surgery
          • Amblyopia
            • Lazy eye: Reduced visual acuity in one eye
            • Pathophysiology
              • Results when one eye does not receive sufficient stimulation
              • Each retina receives different images, resulting in diplopia (double vision)
              • Brain accommodates by suppressing less intense image
              • Visual cortex eventually does not respond to visual stimulation, with resultant loss of vision in that eye
            • Clinical Manifestations
              • Poor vision in affected eye
            • Treatment
              • Preventable if treatment of primary visual defect, such as anisometropia or strabismus, begins before 6 years of age
          • Strabismus
            • “Squint” or malalignment of eyes
            • Esotropia: Inward deviation of eye
            • Exotropia: Outward deviation of eye
            • Pathophysiology
              • May result from muscle imbalance or paralysis, poor vision, or congenital defect
              • Because visual axes are not parallel, brain receives two images, and amblyopia can result
            • Clinical Manifestations
              • Squints eyelids together or frowns
              • Difficulty in focusing from one distance to another
              • Inaccurate judgment in picking up objects
              • Inability to see print or moving objects clearly
              • Closing one eye to see
              • Tilting head to one side
              • If combined with refractive errors, may see any of the manifestations listed for refractive errors
              • Diplopia
              • Photophobia
              • Dizziness
              • Headaches
            • Treatment
              • Depends on cause of strabismus
              • May involve occlusion therapy (patching stronger eye) or surgery to increase visual stimulation to weaker eye
              • Early diagnosis essential to prevent vision loss
          • Cataracts
            • Opacity of crystalline lens
            • Pathophysiology
              • Prevents light rays from entering eye and refracting on retina
            • Clinical Manifestations
              • Gradual decrease in ability to see objects clearly
              • Possible loss of peripheral vision
              • Nystagmus (with permanent visual impairment)
              • Gray opacities of lens
              • Strabismus
              • Absence of red reflex
            • Treatment
              • Requires surgery to remove cloudy lens and replace lens (with intraocular lens implant, removable contact lens, prescription glasses)
              • Must be treated early to prevent permanent visual impairment from amblyopia
          • Glaucoma
            • Increased intraocular pressure
            • Pathophysiology
              • Congenital type results from defective development of some component related to flow of aqueous humor
              • Increased pressure on optic nerve causes eventual atrophy and severe permanent visual impairment
            • Clinical Manifestations
              • Loss of peripheral vision—mostly seen in acquired types
              • Possible bumping into objects
              • Perception of halos around objects
              • Possible complaint of pain or discomfort (severe pain, nausea, or vomiting if sudden rise in pressure)
              • Eye redness
              • Excessive tearing (epiphora)
              • Photophobia
              • Spasmodic winking (blepharospasm)
              • Corneal haziness
              • Enlargement of eyeball (buphthalmos)
            • Treatment
              • Requires surgical treatment (goniotomy) to open outflow tracts
              • May require more than one procedure
      • Trauma
        • Penetrating wounds are most often a result of sharp instruments (e.g., sticks, knives, or scissors) or propulsive objects (e.g., firecrackers, guns, arrows, or slingshots). 
        • Nonpenetrating injuries may be a result of foreign objects in the eyes, lacerations, a blow from a blunt object such as a ball (baseball, softball, basketball, racquet sports) or fist, or thermal or chemical burns
        • Treatment is aimed at preventing further ocular damage and is primarily the responsibility of the ophthalmologist
        • It involves 
          • Adequate examination of the injured eye (with the child sedated or anesthetized in severe injuries)
          • Appropriate immediate intervention, such as removal of the foreign body or suturing of the laceration
          • Prevention of complications, such as administration of antibiotics or steroids and complete bed rest to allow the eye to heal and blood to reabsorb
        • Eye injuries
          • Foreign Object
            • Examine eye for presence of a foreign body (evert upper eyelid to examine upper eye).
            • Remove a freely movable object with pointed corner of gauze pad lightly moistened with water.
            • Do not irrigate eye or attempt to remove a penetrating object
            • Caution child against rubbing eye.
          • Chemical Burns
            • Irrigate eye copiously with tap water for 20 minutes.
            • Evert upper eyelid to flush thoroughly.
            • Hold child’s head with eye under a tap of running lukewarm water.
            • Take child to emergency department.
            • Have child rest with eyes closed.
            • Keep room darkened.
          • Ultraviolet Burns
            • If skin is burned, patch both eyes (make certain eyelids are completely closed); secure dressing with Kling bandages wrapped around head rather than with tape.
            • Have child rest with eyes closed.
            • Refer to an ophthalmologist.
          • Hematoma (“Black Eye”)
            • Use a flashlight to check for gross hyphema (hemorrhage into anterior chamber; visible fluid meniscus across iris; more easily seen in light-colored than in brown eyes).
            • Apply ice for first 24 hours to reduce swelling if no hyphema is present.
            • Refer to an ophthalmologist immediately if hyphema is present.
            • Have child rest with eyes closed.
          • Penetrating Injuries
            • Take child to emergency department.
            • Never remove an object that has penetrated eye.
            • Follow strict aseptic technique in examining eye.
            • Observe for:
              • Aqueous or vitreous leaks (fluid leaking from point of penetration)
              • Hyphema
              • Shape and equality of pupils, reaction to light, prolapsed iris (not perfectly circular)
            • Apply a Fox shield if available (not a regular eye patch) and apply patch over unaffected eye to prevent bilateral movement.
            • Maintain bed rest with child in a 30-degree Fowler’s position.
            • Caution child against rubbing eye.
            • Refer to an ophthalmologist.
      • Postnatal infections
        • The most common eye infection is conjunctivitis.
          • Treatment is usually with ophthalmic antibiotics. 
          • Severe infections may require systemic antibiotic therapy. 
          • Steroids are used cautiously because they exacerbate viral infections such as herpes simplex, increasing the risk for damage to the involved structures
        • Care management
          • Assessment involves 
            • Identifying those children who by virtue of their history are at risk
            • Observing for behaviors that indicate a vision loss
            • Screening all children for visual acuity and signs of other ocular disorders such as strabismus.
          • Nursing alert
            • Suspect visual impairment in a child of any age whose pupils do not react to light
            • Promote parent-child attachment
            • Promote child’s optimal development 
            • Development and independence
            • Play and socialization
            • Education
              • Braille
              • Audio books and learning materials
      • Other disorders
        • Sickle cell disease
        • Juvenile rheumatoid arthritis
        • Tay-Sachs disease