Lesson 3: Measuring Visual Acuity

 

Topic: Vision Part of: Unit: Challenges and Changes: Sensitivity to Vision & Hearing Compromises

 

• Focus: This lesson is designed to teach students some of the underlying principles of measuring visual acuity. Students should be aware that visual acuity is only one of the functional aspects of seeing.

Activities | Introduction | Resources & Web Sites

Activities

Activity 3A: Measuring Visual Acuity

(visual acuity, visual field, depth perception, contrast sensitivity)

Activity 3B: Working with Eye Charts

(graph, diabetic retinopathy, snellen)

Activity 3C: Figuring Visual Acuity

(visual acuity, calculation)

Entire Lesson Download (8 pages)

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Introduction

Lesson 3, "Measuring Visual Acuity" introduces students to the underlying concepts of how visual acuity is measured. Central to this concept is the understanding of ratios. Visual acuity is typically reported as a ratio with the distance for the test being the top number and the angle of resolution (in minutes of arc) the bottom number. Worksheets are provided for students to explore changing ratios with changes in distance and letter height. A visual acuity sheet for near vision (ETDRS) is provided for students to measure each other's acuity at different distances and then graph the results.

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Resources & Web Sites

How Visual Acuity is Measured
http://www.mdsupport.org/library/acuity.html

 

Visual Acuity
http://webvision.med.utah.edu/KallSpatial.html

 

Depth Perception
http://webvision.med.utah.edu/KallDepth.html

 

National Eye Institute - Diagram of the Eye
http://www.nei.nih.gov/health/eyediagram/index.asp

 

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