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Global Blindness: Planning and managing eye care services
Defining visual impairment
Learning outcomes
Describe the World Health
Organization’s classification
of visual impairment
Visual acuity is a measure of
visual performance
Types of visual
acuity chart
• Snellen chart
• Landolt C
• E chart
• LogMAR chart
LogMAR chart
• proportional spacing
• geometric progression
• sans-serif letters
• 5 letters to each line.
Visual acuity
measurements
can be converted
Definition of visual acuity
WHO uses 4 levels of visual function:
• Mild or normal vision
• Moderate visual impairment
• S...
Definition of visual acuity
WHO uses four levels of visual function:
• Mild or normal vision
• Moderate visual impairment
...
Definition of visual acuity
WHO uses four levels of visual function:
• Mild or normal vision
• Moderate visual impairment
...
Measurement of
visual acuity is
based on
distance vision
or visual field
assessment
WHO categories
are based on:
Vision of the better eye
Presenting vision
(not corrected)
WHO
categories of
visual acuity
In summary
Visual acuity measurement is:
• An objective measure of
visual function
• Used to categorise and
define visual ...
Summary
Use the ICD-10 definition
and categorisation of visual
impairment to understand
the epidemiology of
visual impairm...
Written by Dr Daksha Patel
© 2016 International Centre for Eye Health, London School of
Hygiene & Tropical Medicine. This ...
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Global Blindness: Defining visual impairment

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In order to understand the epidemiology of visual impairment we need to use an agreed definition of visual acuity. This will allow us to compare studies from different locations and also measure impact. In this presentation we look at the World Health Organization’s (WHO) classification of visual impairment, which will be used throughout the course. How can this classification be applied to your own work?

© 2016 International Centre for Eye Health, London School of Hygiene & Tropical Medicine. This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International license.

This video is part of the free online course: Global Blindness: Planning and Managing Eye Care Services. We encourage the use and adaptation of this resource for teaching and learning. Find more Open Educational Resources for eye care on our website at http://iceh.lshtm.ac.uk/oer

Published in: Education
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Global Blindness: Defining visual impairment

  1. 1. Global Blindness: Planning and managing eye care services Defining visual impairment
  2. 2. Learning outcomes Describe the World Health Organization’s classification of visual impairment
  3. 3. Visual acuity is a measure of visual performance
  4. 4. Types of visual acuity chart • Snellen chart • Landolt C • E chart • LogMAR chart
  5. 5. LogMAR chart • proportional spacing • geometric progression • sans-serif letters • 5 letters to each line.
  6. 6. Visual acuity measurements can be converted
  7. 7. Definition of visual acuity WHO uses 4 levels of visual function: • Mild or normal vision • Moderate visual impairment • Severe visual impairment • Blindness
  8. 8. Definition of visual acuity WHO uses four levels of visual function: • Mild or normal vision • Moderate visual impairment • Severe visual impairment • Blindness Low vision
  9. 9. Definition of visual acuity WHO uses four levels of visual function: • Mild or normal vision • Moderate visual impairment • Severe visual impairment • Blindness Visual impairment
  10. 10. Measurement of visual acuity is based on distance vision or visual field assessment
  11. 11. WHO categories are based on: Vision of the better eye Presenting vision (not corrected)
  12. 12. WHO categories of visual acuity
  13. 13. In summary Visual acuity measurement is: • An objective measure of visual function • Used to categorise and define visual impairment
  14. 14. Summary Use the ICD-10 definition and categorisation of visual impairment to understand the epidemiology of visual impairment.
  15. 15. Written by Dr Daksha Patel © 2016 International Centre for Eye Health, London School of Hygiene & Tropical Medicine. This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International license. Taken from the free online course: Global Blindness: Planning and Managing Eye Care Services. We encourage the use and adaptation of this resource for teaching and learning. Find more Open Educational Resources for eye care on our website at http://iceh.lshtm.ac.uk/oer

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