1 Visual Acuity Testing CMSft. Lynn Lawrence, CPOT ... - SECO 2011

� Motivation
� Intelligence
Stereo Testing
� Should be done prior to visual acuity testing
Amsler Grid
� Tests the central 20 degrees (macula)
� Each square subtends an angle of 1 0
• Macular Degeneration
• Diabetic Retinopathy
Pseudoisochromatic Plates (PIP’s)
� Ishihara
• 14, 24, or 38 plates
• Plate #1 can be read by anyone, even those with color defects
� Hardy-Rand Ritter (HRR)
• Screening test to separate those with defective color vision from those
with normal color vision
• Classifies the type of defect
• Indicates the extent of the defect (mild, medium, strong)
Farnsworth D-15
� Used to separate medium and strong color defect vs. normal
Color Vision Testing Environment
� Well-lit room
� Natural daylight, without direct sunlight
� MacBeth Illuminant C lamp
� Filtered tungsten halogen light source to provide the most accurate simulation of
natural daylight
Testing Procedures-Children
� Allow child to trace the color with a Q-tip or paintbrush.
� Do not allow the patient to touch the discs with their hands, as dirt and oil can
discolor the plates.
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