Color Vision Deficiency and Ishihara's Test

Colour Vision DeficiencyPresented by :

Optometrist (intern) Asma Al-Jroudi

Saudi Arabia, Riyadh, King Abdulaziz University Hospital

30 Dec 14

• What Is Color Vision Deficiency?

• Causes Of Color Vision Deficiency

• Types Of Color Vision Deficiency

• Tretments Of Color Vision Deficiency

• Ishihara’s Test

• Conclousion

What is Colour Blindness?• Color blindness, or color vision deficiency, is the inability or decreased ability to see color, or perceive color differences, under normal lighting conditions.

•This condition results from an absence of color-sensitive pigment in the cone cells of the retina, the nerve layer at the back of the eye.

What is Colour Blindness?

• Cones are the coulored light receptors in back of the eye: Red light receptors, Blue light receptors and Green light receptors.

• Colour blindness occurs when one or more of the cone types are defected.

Causes of Color Blindness

• Genetic:

Many more men are affected than women.

• Acquired :

Chronic illness, Accidents, Medications and Age.

There are two main types of CVD:• Red-Green deficiency

Where people are unable to distinguish certain shades of red and green; it is the most commonly inherited type..

• Blue-Yellow deficiency

This is a rare condition where it is difficult to distinguish between blue and green, yellow may appear as a pale grey or purple.

Protanopes: do not see RED

Deutranopes: do not see GREEN

Tritanopes: do not see either YELLOW or BLUE

• There is currently no treatment .

• Colour filters or contact lenses can be used in some situations to enhance the brightness between some colours.

• For acquired colour vision deficiency, once the cause has been established and treated, your vision may return to normal.

Treatment

Treatment

• GenetherapySeptember 2009, the journal Nature reported that researchers at the University of Washingtonand University of Florida were able to give trichromatic vision to squirrel monkeys, which normally have only dichromatic vision, using gene therapy.

Ishihara’s test

Ishihara’s test

• The most common is the Ishihara Plate test.

• Can test for red/green colour blindness but not

blue colour blindness.

• This is the test most likely to be used for routine

colour vision screening in schools or medicals.

• Contains 24 plates of circles created by irregular

coloured dots in two or more colours.

Four Different Types of Plates

1. Vanishing design:

Individuals with normal colour vision could recognize the figure.

2. Transformation design:

Individuals with colour vision defect should see a different figure from individuals with normal color vision.

Four Different Types of Plates

3. Hidden digit design:

Only individuals with colour vision defect could recognize the figure.

4. Classification design:Intended to determine the type of color vision defect ( protanopia or deuteranopia) and the severity of it.

Steps & Procedure

1. Obtain the chart in the back of the book

Note: before adminstering this test; you should be tested first.

2. Explain the procedure to the pt.

3. Ask pt first to read the plates with both eyes (with a corrective glasses if there is one)

4. Test pt’s monocularly, one eye at a time.

5. Record those frames the pt misses.

Implementation of Ishihara’s test

Plates 1-17

each figure would be recognized within 3 sec or less.

Plates 1-17

1st plate=12

normal and colour vision deficiencies people will read it 12

Plates 1-17

2nd =8 3rd=29

• Red-green deficiency would read it as:

2nd plates=3 , 3rd plate= 70

• Those with total colour blindness cannot read any figures.

Plates 1-17

4th = 5 5th = 3 6th = 15 7th = 74

• Red-Green deficiency will read it as :4th =2 , 5th = 5, 6th=17, 7th=21

• Those with total color blindness cannot read any figures

Plates 1-17

• 8th =6 ,9th=45 ,10th =5 , 11th =7 ,12th =16 ,13th =73

• Majority of thoes with CVD can not read them or read them incorrectly.

Plates 1-17

14th & 15th plates

• Normal and total colour blindness people can not read any numeral.

• Only thoes with Red-Green deficiency can read them as: 14th= 5 ,15th=45

Plates 1-17

16th=26 17th=42

• protanopic would read it as:

16th=6, 17th=2

• Deutaneropic would read it as:

16th=2 , 17th=4

Plate no. 18

• In tracing the lines between the two X’s, the normal trace along purpule and red lines.

• In protanopia and strong protanomalia Purpleline is traced.

• In deutaneropia and strong deutanomalia Red line is traced

Plate no.19

• Majority of normal and thoes with total colour blindness are unable to follow the line.

• In tracing the line between the two X’s majority of thoes with Red-Green deficiencies trace along the line.

Plate no.20

• Normal will trace the bluish-green line.

• The majority of thoes with colour vision deficiencies are unable to follow the line.

Plate no. 21

• Normals will trace the orange line.

• The majority of thoes with colour vision deficiencies are unable to follow the orange line or will follow a different line.

Plate no. 22

• Normals will trace the the line that connects the bluish-green and yellowish-green lines.

• Red-Green deficiencies will trace line connecting bluish-green and purple.

• Thoes with total colour blindness can not trace any line.

Plate no.23

• Normals will trace the line connecting purple and orange

• Red-Green deficiencies will trace line connecting bluish-green and purple.

• Thoes with total colour blindness can not trace any line.

Plate no. 24

All can trace it easily

Analysis The Results

• If 13 (out of 24) or more plates are read normally, the color vision is regarded as normal.

• If only 9 or less than 9 plates are read normally, the color vision is regarded as deficient.

Conclosion

• Colour blind people face many difficulties in everyday life.

• Problems can arise in even the most simple of activities including choosing and preparing food, gardening, sport, driving a car and selecting clothing.

• Colour blind people can also find themselves in trouble because they haven’t been able to pick up a change in someone’s mood by a change in colour of their face.

Any Questions ?