defective colour vision 1
DESCRIPTION
The presentation is on the various defects of color perception by a human being owing to the defects known as defective color visionTRANSCRIPT
Rena Mehta; Asstt Prof,Jaipur
EYE IS A WONDERFUL ORGAN WITH WHICH WE ENJOY THE BOUNTIES OF NATURE
IMAGINE A WORLD DEVOID OF COLOUR
COLOUR HAS ALWAYS FASCINATED US,
ON GROUND IN AIR
IN WATER
COLOUR CAN BE BROADLY DEFINED AS THE EFFECT ON THE
BRAIN OF AN OBSERVER WHEN AN OBJECT IS VIEWED IN PRESENCE
OF A LIGHT SOURCE.
74%
10%
16%
NORMAL PERSON
Colour blindness is the inability to distinguish certain colours.
It occurs when one or more of the cone types is missing or defective to any extent.
They may be absent entirely, or may be present, but unable to manufacture the necessary signals to the brain.
CONGENITAL ACQUIRED
CAUSES OF DEFECTIVE COLOR VISION
CLASSIFICATION OF
DEFECTIVE COLOUR VISION
Main type Sub type DEFECTIVE COLOUR SYSTEM
Trichromatic
Normal -
Protanomalous Red
Deuteranomalous Green
Tritanomalous Blue-yellow
Dichromatic
Protanopia Red
Deuteranopia Green
Tritanopia Blue-yellow
Monochromatic
SINGLE CONE VISION
LIMITED ROD BASED VISION
Red-green,blue-yellow
Red-green,blue-yellow
C LA SS IF IC AT ION OF DE FE C T IVE C OL OU R V ISION
N O R M A L D E U T R A N A M O U S LY
P R O T A N O M A L O U S T R IT A N O M A LO U S
T R I C R O M A T IC
P R O T O N O P IA D E U T R O N A P IA
T R IT A N O P IA
DI C H R O M A T IC
R O D C O N E
M O N O C H R O M A T IC
DE F E C T I V E C O L O U R V I S I O N
ANAMALOUS TRICHROMATES
ABNORMAL TRICHROMATS WHO ARE NOT DEFICIENT
IN RESPECT OF THEIR VISION OF ANY OF THE SPECTRAL COLOURS,
BUT HAVE AN ABNORMAL INCREASE OR DECREASE IN SENSITIVITY
IN CERTAIN REGIONS
Anomalous trichromatwith a shift in red sensitivity
PROTANOMALY
Anomalous trichromatwith a shift in green sensitivity
DEUTRANOMALY
Dichromats have two cone receptors rather than three, and match all the spectral hues
using two colour matching variables. There are three types of
dichromatism depending on which of the three normal pigments is missing.
Protanopes are the most common, lacking the long-wave ‘red’ sensitive receptors.
Deuteranopes lack the middle-wave ‘green’ receptors, and Tritanopes lack the short-wave ‘blue’ sensitive receptors.
Protanopes and deuteranopes cannot distinguish red light from green light,
while the rare tritanope has blue-yellow confusion2.
DICHROMATS
Available light without red.(red-insensitive dicromat)
Green perceived as both red and green.
(red-insensitive dichromat)
Available light without green.(green-insensitive dichromat)
Red perceived as both red and green.
(green-insensitive dichromat
RELATING TO PROBLEM WITH RED RECEPTION
RELATING TO PROBLEM WITH GREEN RECEPTION
PROTAN
DEUTAN
PROTAN
DEUTAN
STANDARD
16 COLOUR PALETTE
STANDARD PALETTE PROTAN PALETTE
DEUTRON PALETTE
PROTAN PALETTE
DEUTAN PALETTE
Monochromats cannot discriminate colors and perceive only shades of gray.
Individuals with monochromatic vision are truly colorblind (achromatopsia).
There are two types of monochromats. Rod monochromats completely lack cones.
This condition is associated with reduced visual acuity, hypersensitivity to light (photophobia) and other vision impairments
Cone monochromats have only one cone type. They usually have good
visual acuity and none of the other vision impairments found in rod monochromats.
MONOCHROMATS
NORMAL VISION
ROD MONOCHROMATS CONE MONOCHROMATS
This condition is associated
with reduced visual acuity,
hypersensitivity to light (photophobia) and other vision impairments
They usually have good
visual acuity and none of the other vision impairments
found in rod monochromats.
INHERITANCE OF
DEFECTIVE COLOUR VISION
X Y XX
X X X Y X XX Y
WHEN FATHER HAS DEFECTIVE COLOUR VISION
X Y XX
X X X Y X XX Y
WHEN FATHER HAS DEFECTIVE COLOUR VISION AND MOTHER
IS A CARRIER OF RECESIVE CHROMOSOME
X Y XX
X X X Y X XX Y
WHEN MOTHER IS A CARRIER OF DEFECTIVE CHROMOSOME
X Y XX
X X X Y X XX Y
WHEN MOTHER HAS DEFECTIVE COLOUR VISION