History and Present Technology

Source:  History and Present Technology    Tag:  color blindness corrective lenses
1798 - John Dalton, an English scientist who had red-green color blindness, drafted a paper on the topic, entitled “Extraordinary facts relating to the vision of colors,” in which he hypothesized that the source of color perception is obtained from a ball of colored liquid inside the eye. This was disproven after his death, when his eye was analyzed.
1800s - A theory for human color vision was proposed by Thomas Young and Hermann von Helmholtz, which brought about the basics of this deficiency.
1917 - A test was developed, called the Ishihara Color Test. Colored plates with colored dots that were arranged in certain patterns were presented to the patients. With normal vision, the number could be discerned, or nothing can be seen at all, but a patient with color vision deficiency would be able to detect different numbers on the plates.
Now - Four companies (ColorMax, ColorView, ChomaGen, and ColorLite) have joined to develop tinted lenses that modify the way light enters the eyes. The change in the way light enters the eye causes the brain detects the difference and  uses the information to increase focus on the colors detected. Dr. Thomas Azman, working the the companies, developed the ColorCorrection System, corrective contact lenses that allow people with color vision deficiencies, especially deuteranomaly and protanopia, to enhance color vision. The filters alter the wavelengths of the colors going into the eyes and the corrective lenses tints the shades of colors and allows for viewing of normally undetected colors. However, they do not cure color vision problems, as they only improve the situation for more comfortable viewing.  
EnChroma’s recently developed CX sunglasses also are directed at deuteranomaly and protanopia. The glasses filter and reduce the transmission of wavelengths, allowing the colors of green and red to stand out. However, the CX sunglasses also have their problems - they are not permanent measures of treatment nor are they efficient, as colors are dimmed to make red and green stand out.
Researchers at the University of Washington used New World monkeys (Saimiri sciureus) to experiment on, and received successful results in 2009, when the two dichromatic monkeys, Dalton and Sam, were able to become trichromatic monkeys.  The adult monkeys were color blind  since birth, and the researchers experimented to correct this problem. The researchers used gene therapy to correct the lack of L opsin, which provides the information for cones that are sensitive to long, red wavelengths. OPN1LW was genetically engineered  and transcripted into the AAV (adeno-associated viral) genome by using the L/M opsin promoters and L/M opsin enhancers were also used to increase the expression of the gene. Before the treatment, the monkeys were trained to complete the Cambridge Color Test for recognition of the color red. The researchers then injected the virus particles into three different areas of the retina. Over time, sensitivity towards the color red was shown through the Color Test and a multicolor mf-ERG (multifocal electroretinogram system) detected the increase of the cone cell population by stimulating and measuring electromagnetic field signals from the living cells.