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Decreased Visual Acuity

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Decreased Visual Acuity, Visual Impairment, Low Vision, Vision Loss, Optical Low Vision Aid

  • Epidemiology
  1. Incidence of Low Vision increases with age
    1. Affects 3-4% of patients over age 40 years old
    2. Affects 7% of patients over age 65 years old
    3. Affects 25% of patients over age 80 years old
  • Symptoms
  • Normal changes related to aging
  1. Presbyopia
  2. Decreased contrast sensitivity
  3. Decreased dark-light adaptation
  4. Delayed glare recovery
  • Symptoms
  • Abnormal
  1. See Acute Vision Loss
  2. Loss of central vision
    1. Age-Related Macular Degeneration
  3. Loss of peripheral vision
    1. Glaucoma
  4. Generalized loss of vision
    1. Cataract
    2. Diabetic Retinopathy
  • Causes
  • Common (over age 40 years)
  1. See Acute Vision Loss
  2. Age-Related Macular Degeneration (54% of all blindness in U.S.)
  3. Cataracts (most common cause of blindness worldwide)
  4. Glaucoma
  5. Diabetic Retinopathy (present in up to 10% of diabetes patients at time of initial diagnosis)
  • Interpretation
  1. Low Vision
    1. Central vision 20/70 in best seeing eye with best correction OR
    2. Total visual field loss of 140 degrees
  2. Mild Vision Loss
    1. Vision 20/30 to 20/70
    2. Visual field <30 degrees
  3. Moderate Vision Loss
    1. Vision 20/80 to 20/160
  4. Severe Vision Loss (legal blindness)
    1. Vision 20/200 to 20/400
    2. Visual field <20 degrees
  5. Profound Vision Loss
    1. Vision 20/500 to 20/1000
  6. Near Total Blindness
    1. Can detect hand motions
    2. Light perception intact
  7. Total Blindness
    1. No light perception
  • Evaluation
  • Indications for eye care specialist referral
  1. Acute Vision Loss (emergent)
  2. Uncorrected vision <20/50 or
  3. One line difference (on Snellen Chart) between eyes
  • Management
  • Vision Enhancing Devices
  1. See specific conditions
  2. Magnification Devices for reading
    1. High powered prismatic spectacles
    2. Handheld magnifier
    3. Stand magnifier
  3. Magnification Devices for more intricate activities
    1. Telemicroscopes (spectacle-mounted telescopes)
    2. Telescopes
  4. Adjunctive vision devices
    1. Filters to enhance contrast
    2. Filters to reduce glare
  5. Electronic vision Assistive Devices
    1. Video magnifiers
    2. Computer voice synthesizers to read text
  6. Other options
    1. Large print books
    2. Audiobooks
  • Prevention
  1. See Preventive Eye Examination
  2. Low Vision may be preventable in up to 40-50% with periodic Vision Screening
  3. See Home Modifications for Vision Impaired Patients
  4. General measures
    1. Tobacco Cessation
    2. Sunglasses (limit ultraviolet light exposure)
    3. Control comorbid conditions
      1. Diabetes Mellitus
      2. Hypertension
      3. Hyperlipidemia
  • Complications
  1. Major Depression
  2. Social withdrawal and isolation
  3. Loss of independence
  4. Increased fall risk
  5. Hallucinations
  6. Higher risk of older adults being institutionalized
  7. Higher risk of medication errrors
  8. Increased all cause mortality
  • Resources
  1. American Council of the Blind
    1. http://www.acb.org
  2. American Foundation for the Blind
    1. http://www.afb.org
  3. Jewish Guild for the Blind
    1. http://www.jgb.org
  4. Lighthouse International
    1. http://www.lighthouse.org
  5. National Federation of the Blind
    1. http://www.nfb.org
  6. Prevent Blindness America
    1. http://www.preventblindness.org
  7. VisionAWARE
    1. http://www.visionaware.org