What is the Ishihara test?
The Ishihara test is a color eyesight test for detecting red-green color defects. It was named after its creator, Shinobu Ishihara, a University of Tokyo professor who first publicized his trials in 1917.
The test consists of several Ishihara plates, which are a type of pseudoisochromatic plate. Each Ishihara plate shows a solid circle of colored dots, seeming randomized in coloring & size. In the Ishihara plates, the picture (plates) is formed by random colors with different shapes and sizes. It is easily visible to normal color vision and unidentifiable in color-blind people, especially those with red-green vision defects. Other plates are intentionally designed to reveal numbers only to those with a red-green color vision deficiency and be invisible to those with normal red-green color vision. The complete test consists of 38 plates, but a severe defect is usually noticeable after only completing a few plates.
What are the Plates in the Ishihara test?
The plates have various test designs:
Demonstration plates: (first plate of numeral "12") was designed to be noticeable by all persons, whether normal or color vision deficient. For demonstration purposes only and usually not considered in making a score for screening purposes.
Transformation plates: a person with a color vision defect should see a different image or digits from someone with normal color vision.
Vanishing plates: only a person with normal color vision could see the image/plate.
Hidden digit plates: only a person with a color vision defect could see the figure.
Diagnostic plates: To determine the type of color vision defect, or we can say (protanopia or deuteranopia) and the sharpness of it.
Tracing plates: Individuals are asked to recognize a visible line across the image or plate instead of reading a number.
How does the Ishihra test work?
Ishihara test checks the red-green color blindness in those with color vision deficiency. The test will ask you to look at and recognize the series of circles (plates) with different colored dots and sizes. In which dots are formed with other shapes or one or two-digit numbers. If you can't see the red and green, then those shapes of plates will be hard to see or recognize, or you may not see them at all.
What are the four types of color blindness?
There are various types of colour blindness that cause problems seeing different colours.
Red-green colour blindness
It is the most common type of color blindness, making it hard to tell the difference between red and green when you show these colours.
Types of red-green color blindness:
Deuteranomaly: It makes the green look more like red. Some mild symptoms will be seen that don't affect the person in the way of their daily activities. It is the most common type of red-green type.
Protanomaly:It makes red look greener and lesser intense (bright). In this type, the symptoms are also mild and usually don't get in the way of daily activities. Protanopia and deuteranopia: In this type, the person won't be able to tell the difference between red and green shows on the plate or in real-life activities.
Blue-yellow color blindness: Blue-yellow color blindness is the less common type of color blindness, making it harder to tell the difference between yellow-red and blue-green.
There are two sub-types of blue-yellow color blindness:
Tritanomaly: In tritanomaly, the person will find it hard to tell the difference between yellow and red and blue and green.
Tritanopia: In tritanopia, the person cannot distinguish between purple and red, yellow and pink, and blue and green. It also makes colours look less intense.
Complete color blindness: In complete color blindness, you can't see any colours at all. This type is also called monochromacy, and it's an uncommon type, and the probability is significantly less. Depending on the class, you may also need help seeing with clear vision and sensitivity to light.
What causes poor color vision?
Color vision deficiency affects the inability to distinguish specific colors in daily activities. The following conditions can cause color vision deficiency:
- 1. Genetics
- 2. Maturing (Aging)
- 3. Certain medications and disorder
- 4. Hazard to chemicals
According to a survey of colour-blind professionals, "1 in 12 men and 1 in 200 women experience color blindness". The majority of people with color blindness have inherited the condition.
Sometimes, problems with color vision deficiency are due to an illness affecting your optic nerve, such as glaucoma. Color vision deficiency can also result from an inherited issue with your retina's cones (called colour-sensitive photoreceptors ). The retina is the most light-sensitive layer at the back of your eye.
Certain diseases can cause color vision deficiency, including:
- 1. Diabetes
- 2. Alcohol
- 3. Macular Degeneration
- 4. Leukemia
- 5. Alzheimer's Disease
- 6. Parkinson's Disease
- 7. Sickle Cell Anemia
You can cure color vision deficiency by receiving treatment for the underlying condition.
Who needs to pass a color blind test?
Many jobs require one to pass the color-blind test. Career paths include the fire department, railway department, police department, Army, Coast Guard officers, Aeroplane pilots, and more. To work or serve in these departments, people must pass the Ishihara color blind test. Except for these departments, it's optional or essential they may be allowed to use color vision lenses. Many people also wear color vision lenses to improve and enhance their color vision on their job.
With our Ishihara color blind test, people can know their color blindness and pursue a career that was previously off-limits by doing treatment in underlying conditions.