Color is not an inherent property of matter; it is a sensation created by the brain. When the machinery of the eye fails to capture specific wavelengths, entire spectrums of reality disappear. This is the world of Color Vision Deficiency (CVD).
The Cone Mosaic
The human retina contains three types of cone cells, each tuned to a specific wavelength peak:
- L-Cones: Long wavelengths (Red).
- M-Cones: Medium wavelengths (Green).
- S-Cones: Short wavelengths (Blue).
Our brain compares the signals from these three cones (Trichromacy) to perceive millions of colors. When one type of cone is missing or anomalous, the brain loses the ability to distinguish between certain hues.
Types of Color Blindness
Using our Color Blind Test, users can screen for the following conditions:
Deuteranomal (Green-Weak)
The most common form, affecting roughly 6% of males. The green cone is present but shifted toward the red spectrum, creating a "confusion line" where red and green look identical.
Protanopia (Red-Blind)
The complete absence of L-cones. Red looks dark or black, and purple is indistinguishable from blue.
The Ishihara Mechanism
Developed by Dr. Shinobu Ishihara in 1917, the pseudoisochromatic plates used in our test work on the principle of "confusion colors." Dots are arranged such that a trichromat (normal vision) sees a pattern based on hue, while a color-blind person sees a random field of brightness noise.
Curious about your own spectral sensitivity? Take the Ishihara Color Blind Test now.