Cone Contrast Background
description
Transcript of Cone Contrast Background
Every Airman a Force Multiplier
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Cone Contrast TestAerospace Ophthalmology
USAF School of Aerospace Medicine711th Human Performance Wing
Cone Contrast Test (CCT)
Every Airman a Force Multiplier
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Hereditary color deficiency 8% of males1 in 200 females
Current tests detect presence of color deficiencyFew tests detect
Type (red, green, blue)Severity of deficiency
Introduction
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Based on normal color visionLetters visible to single cone typeIn decreasing steps of visibility(cone contrast)Lowest visiblecone contrast
Cone Contrast Test
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Quantifies normal color visionType & severity of hereditary deficiencyAcquired color loss in eye disease
Cone Contrast Test
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Red Cone Contrasts
1 V Z N F U2 F V N H P3 R P F D U4 Z E D H P5 H R P E D
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Green Cone Contrasts
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1 H V R N F2 D R E Z U3 N Z V E P4 Z E D N F5 H R P E D
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Blue Cone Contrasts
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1 D R E Z U2 F V N H P3 R P F D U4 N Z V E H5 H R P E D
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Hereditary Color Deficiency
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1 V Z N F U2 F V N H P3 R P F D U4 Z E D H P5 H R P E D6 D R E Z U
1 V Z N F U2 F V N H P3 R P F D U4 Z E D H P5 H R P E D6 D R E Z U
1 V Z N F U2 F V N H P3 R P F D U4 Z E D H P5 H R P E D6 D R E Z U
Normal perception Red deficiency
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Hereditary Color Deficiency
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Normal perception Green deficiency
1 H V R N F2 D R E Z U3 N Z V E P4 Z E D N F5 H R P E D6 F V N H P
1 H V R N F2 D R E Z U3 N Z V E P4 Z E D N F5 H R P E D6 F V N H P
1 H V R N F2 D R E Z U3 N Z V E P4 Z E D N F5 H R P E D6 F V N H P
1 H V R N F2 D R E Z U3 N Z V E P4 Z E D N F5 H R P E D6 F V N H P
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CCT Detects Color Deficiency
0 4
0
25
50
75
100
Cone Contrast Test
CCTScore
Red Green Blue
Hereditary Color Deficiency
mean
+3SD
-3SD
NormalsRed deficientGreen deficient
NormalsRed deficientGreen deficient
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CCT Grades Color Performance
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0 10 20 30 40 50 60 70 80 90 100
CCT Score (right Eye)
CCT Score (left Eye)
> 2SD
Normal upper right quadrant
75
75
Green deficiency (n=183)Red deficiency (n=43)Normals (n=92)
In color deficiency and in normals
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Acquired Color Deficiency:Eye Disease
Visual Pathway
NormalsRetinaOptic Nerve
Red Green Blue
CCT in Eye Disease
Acquired Color Deficiency
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25
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75
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CCTScore
Cone Contrast Test12
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N
V
R
E
U
ZZ Single letter
CCT Different
(random)sequence each time
Prevents memorization
Automated CCT
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Brief Demo of Netbook CCT
Pre-calibrated Netbook with CCT programUser friendly; patient responds with mouseRapid staircase to threshold; automatic scoring
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Use Mouse to Select the Letter You See; Computer-Voice Reports Your Response; Letter contrast decreases with
correct response; increases with incorrect response
CCT Task
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Program Continues until Red, Green and Blue Tests are given to Right Eye and then Left Eye
(just follow the prompts)
CCT Task
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Recent CCT Results
Red Deficient
GreenDeficient
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CCT Calibration VerificationUser is Prompted Weekly
When prompted, Plug Spyder3 into Netbook USB Port; Place Spyder3 on Measuring Area as Shown; Select Start; Program will require 3-5 minutes
to check calibration and re-calibrate if not within tolerance.