At our vision center in Salem, our team at the Medical Center Eye Clinic receives a lot of questions from curious patients about what makes their eyes tick. Quality vision means more than just having a comfortable pair of contacts or stylish eye glasses. Great vision comes from understanding how the eye functions, and prescribing the corrective lenses necessary to provide your eyes clearer, sharper focus.
The complex process of how our eye focus light into vision begins with the spectrums of light perceived by the retina, the thin nerve layer at the back of the eye. The retina is made up of two different types of cells, called “rods” and “cones”, named for their distinctive shapes. The cones, which function less effectively in dim light than the rods, are responsible for our color vision. That’s why it’s hard to distinguish colors in dim light when rod function is primarily responsible for our vision.
There are three types of cones, classified as red, green, and blue receptors, each sensitive to a different range of wavelengths in the visible color spectrum. Color perceptions are based on the differential stimulation of the three types of cones. The sensation of white is produced when all three types are stimulated simultaneously, and yellow is produced by the stimulation of the red and green types. A person can have a deficiency in one, two or all three types of cone function, resulting in some form of color blindness.
Color blindness can be acquired or hereditary. Acquired color blindness develops as the result of diseases of the cones or their connections in the retina, optic nerve, or brain. Hereditary color blindness affects approximately 7% of all men and less than 1% of women. By far the most common type of color blindness affects the red and green systems, making it difficult for patients to distinguish between some shades of green and reds. The inability to distinguish between yellows and blues is much less prevalent, and total color blindness – seeing the world only in shades of grey and white – is extremely rare.
While color blindness may certainly be a nuisance, making it difficult to choose clothes that match, for example, or pick strawberries (for those with red-green color blindness), it is generally not a disabling problem. An obvious question concerning red-green color blindness involves driving: How does a color blind person know when to stop and go at traffic signals? Interestingly, for quite some time, traffic lights have been manufactured in shades of red and green that even color blind people can easily distinguish.
If you have trouble distinguishing colors or your vision isn’t as sharp or clear as it once was, schedule an appointment at our vision center in Salem. Our experienced team of eye health professionals can provide clarity about the causes of your poor vision, and offer a wide selection of stylish eye glasses and comfortable contacts perfect for any prescription.