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