The analysis of color is mainly due to the cone cells concentrated in the central fossa of the retina. When these cells lose the ability to distinguish colors, it causes color blindness.
A pair of sex chromosomes (XX in females and XY in males) are involved in the mutations that cause color blindness, an inherited disease. People with color blindness have a mutation or lack of a gene on the X chromosome, which causes a disorder of the light-sensitive cells in the eye that are needed to distinguish colors.
People with color blindness have a reduced ability to perceive colors. The risk of color blindness in men is higher than in women. There are many factors that cause color blindness, including:
Congenital: The patient loses the ability to see blue or yellow.
Due to side effects of drugs: Some drugs have the ability to affect such things as cardiovascular drugs, blood pressure, infections, neurological disorders, etc.
Due to complications when suffering from some chronic diseases: diabetes, cardiovascular disease, Alzheimer's,
Due to aging,  eyesight and the ability to distinguish colors also decrease with increasing age, causing color blindness in the elderly.
Manifestations of color blindness
People with color blindness often do not know they have it because they can still distinguish other colors but cannot distinguish certain colors.
Mild degree, it is often difficult to distinguish colors such as green from red and blue from yellow.
The severity does not distinguish the colors from each other.
You can check your status with the  color blind test tool. Online application, free, high accuracy.