Tag Archive retina


Smoking Weed May Improve Night Vision

Smoking Weed May Improve Night Vision

Cannabinoid Receptors In Retina Make Cells Sensitive To Light

Originally posted at medicaldaily.com

Growing up, you likely learned about a list of veggies, including Vitamin-A rich carrots, that can improve your eyesight, but marijuana probably wasn’t on that list. Now, researchers from the Montreal Neurological Institute suggest smoking weed may help your night vision by decreasing the eyes’ sensitivity to light.

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The belief marijuana could improve, not impair, vision goes against conventional wisdom. One of the drug’s key effects on eye health is redness. THC, the drug’s active ingredient, lowers blood pressure, which dilates the blood vessels and increases blood flow to the body. This leads the blood vessels in the eye to expand and causes redness or bloodshot eyes. But researchers found applying a synthetic cannabinoid to eye tissue can make cells more sensitive by increasing the rate they fired to both bright and dim light stimuli.

“Initially you distrust yourself when you see something that goes against widely held ideas, but we tried the experiment so many times, using diverse techniques, and it was a consistent result,” said Ed Ruthazer, senior author of the paper, and a professor of neurology and neurosurgery at the Montreal Neurological Institute of McGill University, in a statement.

In the study, published in the journal eLife, Ruthazer and his colleagues applied synthetic cannabinoids to the eye tissue of tadpoles of the African clawed toad in one group, while the other group acted as a control. Researchers chose to observe tadpoles because like humans, their eyes also contain CB1 protein, which binds the psychoactive ingredient of marijuana (THC). They used microelectrodes to measure how retinal ganglion cells, whose fibers form the optic nerve, respond to light.

The tadpoles were then placed in a petri dish that was dotted with black marks on the outside shaped to look like the shadows of predators. Typically, tadpoles will avoid the dark as a defense mechanism to stay safe from predators.

Girl and smoke Smoking weed may help you see better in the dark, and act as treatment for degenerative eye diseases. Photo courtesy of Pexels, Public Domain

The findings revealed there was heightened activity in the presence of the cannabinoids in the retina. Meanwhile, when the lights were turned down, tadpoles given cannabinoids were more effective at avoiding fearsome marks than their sober counterparts. Researchers suspect the improved vision is linked to how the preoccupied CB1 receptors caused a decrease in the number of negatively charged chloride ions that traveled inside the neurons. This causes the membranes to become hyperpolarized, which leads to more electrical activity.

Although this gives some insight that marijuana could someday be used as a medical treatment to degenerative eye diseases, like retinitis pigmentosa, the results warrant further investigation, authors said.

“Our work provides an exciting potential mechanism for cannabinoid regulation of neuronal firing, but it will obviously be important to confirm that similar mechanisms are also at play in the eyes of mammals,” said Ruthazer.

In a similar 2004 study in the Jourrnal of Ethnopharmacology, researchers traveled to the Rif mountains in Morocco to observe the effects of marijuana on night vision. The researchers gave synthetic cannabinoid to one volunteer, and hashish to three more, and then measured the sensitivity of their night vision before and after. Marijuana improved night vision in all three participants. However, the study did not explore why vision improved.

The method hasn’t been tested on people yet, but it does provide hope for treatments for debilitating eye diseases like glaucoma, which causes blindness by killing off cells in the retina. Cannabinoids are actually known to have a neuroprotective effect on retinal cells.

Source: Miraucourt LS, Tsui J, Gobert D et al. Endocannabinoid signaling enhances visual responses through modulation of intracellular chloride levels in retinal ganglion cells. eLife. 2016.

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Search for Genes Causing Eye Disease


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retina cons and rods

retina cons and rods

Genes and Vision loss.  The retina is a thin, light-sensitive tissue at the back of the eye. It captures light and converts it into a chemical signal which travels to the brain, ultimately registering as vision. The retina is actually part of the central nervous system and is considered part of the brain. The ‘photoreceptors’ or light-sensitive nerve cells of the retina, are divided into the rod cells and the cone cells, reflecting their actual shapes.

There are about 120 million rod cells spread throughout the retina. These are responsible for black and white vision, and allow vision in low-light conditions. Then the six million cone cells are located in the centre of the retina, in an area called the macula, and are responsible for colour vision and detailed central vision.

A group of diseases collectively called inherited retinal degenerative disorders are caused by genetic defects which cause vision loss. This may result in total blindness. These disorders are caused by genetic changes or mutations and are inherited within families.

These genetic mutations result in different disorders. Gene defects affecting mainly the rod photoreceptors cause retinitis pigmentosa. As a result patients experience night blindness and loss of peripheral vision, causing a tunnel-like vision. Genetic mutations causing a primary loss of cone photoreceptors result in Stargardt disease or macular degeneration and cause a loss of central vision.


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Mission to help these people see

Originally posted by Canada.com / © Copyright (c) The Daily Telegraph



Macular degeneration is one of those conditions that most people approaching late middle-age dread. For many of the 90,000 diagnosed annually, blindness is inevitable. But one man is determined to change this: Ahmed Nagiati El-Amir, who at 37 is already considered one of Europe’s leading eye surgeons.

Mr El-Amir discovered his vocation while still a student at Charing Cross Hospital medical school.

“We did very little ophthalmology but the little we did do interested me, so I decided to educate myself,” he says.

He started attending the weekly 7am ward rounds of Professor Alan Bird, a renowned surgeon at the Institute of Ophthalmology at Moorfields Hospital, in London. The professor told him to go away; ward rounds were for trainee eye surgeons, not students. But he persisted, and the irritated prof started firing questions at him. El-Amir’s extracurricular studying paid off and he held his own. Prof Bird took him under his wing and guided him from them on.

After training at Moorfields, Mr El-Amir was a consultant ophthalmic surgeon at 32. He now works across several NHS hospitals in Berkshire and his private practice in Harley Street.

It was Prof Bird who set him on his current course. “I remember him saying to me that with the right innovation, in 10 or 20 years, eye surgeons would be treating patients for whom once we could do nothing. I felt challenged by this,” he recalls. And so he focused on macular degeneration.

The macula is a part of the retina – the back of the eye – responsible for central vision. The degeneration typically represents a tiny spot on the back of the eye, not much larger than a full stop. Yet it relates to a field of vision equivalent to two or three laptop screens. As this is in the centre of vision, it is particularly disabling: while retaining peripheral vision, sufferers become unable to see faces or read.

Macular degeneration usually affects people over 60 and is the leading cause of blindness in the UK. It is broadly divided into two categories: “wet” and “dry”. While both result in the same central blind spot, they are different diseases. The wet type, which makes up about 10 per cent of cases, is the result of blood vessels under the macula haemorrhaging and cutting off the blood supply. There are several different treatments which, when injected directly into the eye, can slow the progression. The dry type, which makes up the remaining 90 per cent (around 600,000 people in Britain), is caused by cells responsible for vision withering away. No one knows why this happens, though it’s likely genetics play a part. Its progress is slower than the wet form, but there are few treatments and blindness usually follows.

“It was for these people – those for whom we can do nothing at the moment – that I went into ophthalmology. It is my duty to find a way to help these people see,” says Mr El-Amir.

He has developed a technique using a series of lenses that are inserted into the eye. They act as a telescope, enlarging the image on to the area of the retina that is peripheral to the macula. The brain then does something surprising: it starts to adapt, using the healthy part of the retina to view central images. In effect, the lens system manages to trick the brain into “moving” the macula to another part of the eye not affected by the degeneration.

The technique has been used successfully before, however it was deemed unsuitable for those who had cataracts. Since the vast majority of macular degeneration sufferers – well over 80 per cent – fall into this category, this has been a major problem. Mr El-Amir’s approach enables him to operate on those with a history of cataracts, meaning it could help save the sight of around 500,000 people. His technique involves multiple scans of the eye to understand its unique anatomy, and uses different ways to support the lens once in place.

Mr El-Amir is keen to make the surgery available on the NHS but says he will need personally to train surgeons initially because of the expertise required. The main stumbling block, however, is that the lenses are hand-made and therefore expensive. Still, a cost-benefit analysis for the NHS shows it’s cheaper than providing care for macular degeneration sufferers, especially when accounting for the risk of falls and other injuries to which the visually challenged are prone. There is, moreover, 10 years of data from the US suggesting these lenses do work.

To operate on one eye costs about pounds 15,000, so Mr El-Amir is now working to reduce this. The lens manufacturers say if demand increases, they could cut the price by a third, but NHS managers appear wary of committing themselves. Moorfields Eye Hospital, however, has expressed an interest in helping Mr El-Amir do trials to help convince the health service to offer the treatment nationwide, so he remains optimistic it could yet save the sight of many thousands currently condemned to blindness. “You have to remain positive,” he says. “You have to have hope.”

For more information, visit: macularsociety.org and harleystreeteye.com

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Retina protein that may help conquer blindness discovered



March 4, 2015
Louisiana State University Health Sciences Center
A protein in the retina that is crucial for vision has been discovered by researchers who report, for the first time, the key molecular mechanisms leading to visual degeneration and blindness. The research reveals events that may be harnessed for prevention, as well as to slow down progression of retinal degenerative diseases.

Research led by Nicolas Bazan, MD, PhD, Boyd Professor and Director of the LSU Health New Orleans Neuroscience Center of Excellence, discovered a protein in the retina that is crucial for vision. The paper reports, for the first time, the key molecular mechanisms leading to visual degeneration and blindness. The research reveals events that may be harnessed for prevention, as well as to slow down progression of retinal degenerative diseases. The paper is published in the March 4, 2015, issue ofNature Communications.

There is growing evidence of the significance of the essential omega-3 fatty acid family member, docosahexaenoic acid (DHA), for photoreceptor function and in retinal degenerative diseases, but not much understanding about what governs it. The research team found that the protein receptor for adiponectin, a hormone that promotes insulin sensitivity and is involved in the metabolic syndrome, has a heretofore unrecognized function. The receptor also regulates DHA retention and conservation in cells in the eye and is necessary for photoreceptor cell function.

“This is the first time that such an integral membrane protein has been localized in the photoreceptor cells and shown to have the capacity to support sight,” notes Dr. Bazan, the paper’s corresponding author.

Working with a novel genetic mouse model they developed with the adiponectin receptor gene deleted, the researchers found that total and free retinal DHA were diminished in the gene-deficient mice. When they incubated normal retinas with labeled DHA, they measured abundant levels of it, demonstrating that a functional AdipoR1 gene must be present for DHA uptake and retention. Additionally, when cultured human Retinal Pigment Epithelial (RPE) cells were incubated with labeled DHA, DHA within the medium decreased with time while increasing within the cells. Also, when the AdipoR1 gene activity was ramped up in these cultured RPE cells, much more labeled DHA was taken up and incorporated. But when silenced, labeled DHA was diminished, indicating that human RPE cells can also take up DHA and that the AdipoR1 gene plays a significant role in this activity, too.

DHA in brain and retinal cells also builds reservoirs for molecules called into action when normal functions are disrupted, resulting in such conditions as retinal degeneration, Parkinson’s or Alzheimer’s disease. Dr. Bazan and his colleagues previously discovered neuroprotectin D1 (NPD1), one such molecule made from DHA when cell survival is compromised. Loss of, or diminished, retinal DHA leads to visual impairment and may play an important role in the development of blindness from retinitis pigmentosa and other retinal degenerative diseases, as well as age-related macular degeneration (AMD), the foremost cause of blindness in people older than 50 years.

“Our model and newly discovered molecular mechanism allow therapies to be tested more rapidly,” notes Dr. Bazan. “We feel an urgency to address blindness and cognition impairments of dementias because of their heavy burden on patients, families, care givers and the health care system.”

DHA, found in fish oil, is an essential omega-3 fatty acid and is vital for proper brain function. It is also necessary for the development of the nervous system, including vision. Dr. Bazan has been a pioneer in the understanding of the biology and impact of DHA in medicine.

Story Source:

The above story is based on materials provided by Louisiana State University Health Sciences Center. Note: Materials may be edited for content and length.

Journal Reference:

  1. Dennis S. Rice, Jorgelina M. Calandria, William C. Gordon, Bokkyoo Jun, Yongdong Zhou, Claire M. Gelfman, Songhua Li, Minghao Jin, Eric J. Knott, Bo Chang, Alex Abuin, Tawfik Issa, David Potter, Kenneth A. Platt, Nicolas G. Bazan.Adiponectin receptor 1 conserves docosahexaenoic acid and promotes photoreceptor cell survival. Nature Communications, 2015; 6: 6228 DOI:10.1038/ncomms7228

Cite This Page:

Louisiana State University Health Sciences Center. “Retina protein that may help conquer blindness discovered.” ScienceDaily. ScienceDaily, 4 March 2015. <www.sciencedaily.com/releases/2015/03/150304104514.htm>.

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Grapes in the diet linked to improved eye health

Originally posted by: westernfarmpress

In tests, grapes reduce retinal degeneration
  • Grapes in the diet linked to improved eye health
  • Retinal function
  • New research suggests that consistent grape consumption may improve eye health by protecting the retina from deterioration.
  • A grape-enriched diet in a study with mice protected retinal structure and function.

New research findings suggest that consistent grape consumption may help eye health by protecting the retina from deterioration.

Specifically, a grape-enriched diet protects retinal structure and function.

The retina has cells which respond to light, also known as photoreceptors which includes two types – rods and cones.

Retinal degenerative diseases impact more than five million people in the U.S. The maladies can result in blindness caused by photoreceptor cell death.

The study was conducted by a research team with the University of Miami, Bascom Palmer Eye Institute. The research investigated whether a diet supplemented with grapes could protect the photoreceptors in mice which have retinal degeneration.

Mice were fed a grape-supplemented diet corresponding to three servings of grapes per day for people, or one of two control diets.

The research findings were shared at the recent Association for Research in Vision and Ophthalmology (ARVO) conference in Orlando, Fla.

The research results suggest that retinal function was significantly protected in the mice consuming the grape-enriched diet. In fact, the grape-consuming rodent group had three times more rod and cone photoreceptor responses compared with those on the control diets.

The grape-fed mice also had thicker retinas.

Retinal function

Grape consumption also protected retinal function in a form of macular degeneration. In addition, grape-fed mice had reduced levels of inflammatory proteins and higher amounts of protective proteins in the retinas.

“The grape-enriched diet provided substantial protection of retinal function which is very exciting,” said Abigail Hackam, the study’s lead investigator.

“It appears that grapes may work in multiple ways to promote eye health from signaling changes at the cellular level to directly countering oxidative stress,” Hackam said.

ARVO is the largest eye and vision research organization in the world representing members from more than 70 countries.


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