A new study enhanced color vision for individuals with the most common type of red-green color blindness.
- Special glasses constructed with technically advanced "spectral notch filters" enhance color vision for individuals with the most common type of red-green color blindness.
- The ability for colorblind participants to experience expanded color channels was demonstrated even after they took the glasses off.
- At least 8 percent of men and .5 percent of women have red-green color vision deficiency (CVD).
A new study may be a breakthrough in treating the most common type of red-green color blindness.
Research conducted by UC Davis Eye Center in collaboration with Frances INSERM Stem Cell and Brain Research Institute discovered that special patented glasses constructed with technically advanced "spectral notch filters" enhance color vision for individuals with anomalous trichromacy.
Interestingly, the ability for colorblind participants to experience and discern expanded color channels was demonstrated even when they were not wearing the glasses.
Red-green color blindness
At least 8 percent of men and .5 percent of women have red-green color vision deficiency (CVD). That's 13 million people in the United States and 350 million globally.
Someone with "normal" color vision is able to experience one million hues and shades, but those with CVD see a diminished range of colors. They see colors that are more muted and washed out, and some colors are difficult to distinguish and may cause confusion.
This UC Davis study analyzed the impact of spectral notch filters—EnChroma glasses—on boosting the chromatic responses of observers with red-green CVD over a two-week period of usage. The filters are engineered to increase the separation between color channels to assist colorblind individuals in seeing colors more vibrantly and precisely.
The study, which was published in the journal Current Biology, had participants with CVD color blindness wear either the special filter glasses or placebo glasses.
"Over two weeks, [the participants] kept a diary and were re-tested on days 2, 4 and 11 but without wearing the glasses," UC Davis Health detailed in a news release statement. "The researchers found that wearing the filter glasses increased responses to chromatic contrast response in individuals with red-green color blindness." It's still not clear how long the enhancement to vision lingers after the filtered glasses are taken off, however evidence shows that the effect lasts for a substantial amount of time."Extended usage of these glasses boosts chromatic response in those with anomalous trichromacy (red-green color vision deficiency)," said John S. Werner, a professor of ophthalmology and a leader in vision science at UC Davis Health. "We found that sustained use over two weeks not only led to increased chromatic contrast response, but, importantly, these improvements persisted when tested without the filters, thereby demonstrating an adaptive visual response."
The researchers in this study think that the study's results suggest that modifications of photoreceptor signals activate a plastic post-receptoral substrate in the brain that could possibly be exploited for visual rehabilitation.
"When I wear the glasses outside, all the colors are extremely vibrant and saturated, and I can look at trees and clearly tell that each tree has a slightly different shade of green compared to the rest," said Alex Zbylut, one of the colorblind study participants who got the placebo glasses first and then tried the special filter version afterwards. "I had no idea how colorful the world is and feel these glasses can help colorblind people better navigate color and appreciate the world."
Read the study in Current Biology here.
A new study reveals that it increases eye pressure, negating the effects of THC.
- For decades, marijuana has been touted as providing glaucoma relief.
- A study out of Indiana University shows that while THC reduces eye pressure, CBD does the opposite.
- Of the 18 mice tested, females were less responsive to marijuana than males.
While glaucoma has been the butt of many well-intentioned, wink-wink weed jokes for decades, the disease is quit serious. In fact, glaucoma is the leading cause of blindness in people above sixty. Glaucoma is insidious as well. Abnormally high pressure in your eyes gradually damage the optic nerve.
Vision loss is subtle until it reaches advanced stages, by which point there is little chance of slowing damage. By this point prevention is impossible.
It begins with patchy spots in your vision, mostly in the periphery or central vision. By the time glaucoma is in latter stages, tunnel vision results. Deterioration of the optic nerve is irreversible. Some treatments mitigate damage by lowering eye pressure, such as laser treatment and eye drops.
And, of course, there is marijuana, which does, in fact, lower eye pressure — specifically, THC lowers it. But there are trade-offs. Unlike other treatments, marijuana's effects last 3–4 hours, meaning you need to smoke continuously throughout the day. While pressure is reduced, the constant smoke creates other problems.
However, a new study out of Indiana University reveals that marijuana, specifically cannnabidiol (CBD), can make glaucoma worse.
The study, published in Investigative Ophthalmology & Visual Science on December 14, found that CBD — one of the hottest and, as I've previously written, suspect health trends being shoved into every product imaginable at a premium — actually creates a rise in eye pressure, the exact opposite effect a glaucoma sufferer desires.
Associate scientist Alex Straiker, who led the study, continues:
This study raises important questions about the relationship between the primary ingredients in cannabis and their effect on the eye. It also suggests the need to understand more about the potential undesirable side effects of CBD, especially due to its use in children.
As mentioned, THC indeed lowers eye pressure, which has been the mechanism by which treatment has been administered thus far. The problem is, according to Straiker's research, CBD blocks the pressure-reducing effects that THC offers.
Illustration of glaucoma treatment using ultrasound. The ultrasound beams enable the ciliary body, the gland which produces aqueous humour, to coagulate, reducing the secretion long-term. The optic nerve is no longer under pressure, sight is maintained. Image source: BSIP / UIG via Getty Images
Which makes the science even more paradoxical and troubling for patients: CBD is being advertised as the non-psychoactive wunder drug counterpart to THC, which is what makes you high. Those who crave the benefits of marijuana without the fuzzy feeling find relief in CBD oils, tinctures, and creams. These, however, apparently will not help those with glaucoma because its greatest bioavailability comes from smoking.
It should be noted that this study was conducted on 18 mice. Interestingly, female mice were less affected by THC, which also has implications for marijuana's role in treating glaucoma. More research will have to be conducted on humans, but as Straiker concludes, this research offers new avenues of inquiry.
There were studies over 45 years ago that found evidence that THC lowers pressure inside the eye, but no one's ever identified the specific neuroreceptors involved in the process until this study. These results could have important implications for future research on the use of cannabis as a therapy for intraocular pressure.
The case of a 7-year-old Australian boy who was supposed to lose sight at two weeks old but can still see has stunned scientists.
Researchers in Australia recently presented a study of a 7-year-old boy who is missing most of his visual cortex but surprisingly can still see. It is the first known case of this kind.
When he was only two weeks old, the boy suffered serious damage to his visual cortex, the part of the brain that manages sensory nerve impulses from our eyes, as a result of a rare metabolic disorder called medium-chain acyl-Co-A dehydrogenase deficiency. This condition prevents tissues from converting some types of fats into energy.
The boy, referred to only as “B.I.” by the researchers from the Australian Regenerative Medicine Institute at Monash University, ended up without of his visual cortex. This is usually a situation that would result in cortical blindness, an illness where the brain can still get visual input but cannot process what it is seeing, making the person feel like they have sight but not actually allowing them to see. The boy, however, can see almost anything on par with other kids his age, able to play soccer or video games and read emotions on people’s faces.
The scientists studied the unusual case, hoping to understand what makes B.I.’s condition so unique. Through MRI-scanning they found a remarkable instance of the brain’s neuroplasticity, with the boy’s visual pathway of neural fibers in the back of the brain enlarged. This adaptation means that the pathway allows the boy to see by doing the work of the visual cortex.
"Despite the extensive bilateral occipital cortical damage, B.I. has extensive conscious visual abilities, is not blind, and can use vision to navigate his environment," write the researchers in the study.
You can read their study here.