Part 1 of this report can be found by clicking here: Study links blue light emitted by screens to higher cancer risk

Doctors are concerned about the many hours people are spending on screen time and how it's affecting our eyes.

This time they are not talking about eye irritation and temporary redness, they are talking about permanent damage and blindness for adults and children.

For more than a decade, researchers at Tulane have been uncovering how artificial light at night is harmful. Any light at night keeps your natural sleep hormone melatonin from rising. And there are connections between low melatonin and breast and prostate cancer tumor growth. There are also interruptions with glucose, insulin and fat metabolism. Night-shift workers have much higher cancer rates, and even worse on the light spectrum is the high energy blue light from screens.

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"We're not designed to have high blue frequency CFL fluorescent bulbs that are shining at all hours of the night because what that does is it throws off our circadian rhythms," explained Retina Specialist Dr. Rob Ross, Assistant Clinical Professor of Ophthalmology at Tulane who is also on staff at East Jefferson General Hospital.

Light at night is throwing off sleep and all the repair work our bodies do during sleep in darkness, but now, even more science is emerging about blue light health problems and this time it's about our eyes.

"It is affecting one of the forms of vitamin A that is critical for sight and then changing the shape of the cells that give us vision, and ultimately leading to that cell death," said Dr. Rebecca Metzinger, Chief of Ophthalmology at Veterans Health Care System in New Orleans and an Associate Professor of Ophthalmology at Tulane.

Dr. Metzinger says she is rethinking all of her exposure to screen time and the amount her children get too.

"And so the question will be, will we start seeing younger people with macular degeneration, with the amount of exposure, because interestingly enough, children's eyes absorb much more blue light than adults," she explained.

"The retina continues to develop way into the teens, and with these kids with these smart phones, you know, looking at all this blue light at all hours of the night," said Dr. Ross.

Dr. Ross is a retina specialist who assisted on the surgery of the late Mother Teresa. His concern is that this kind of eye tissue doesn't act like skin or bones when damaged. It acts like the brain or spinal cord.

"We have a fixed amount of rods and cones," he said, speaking about the cells in the eyes. That's why this is bad. If you get damage, this is neural tissue. It doesn't regenerate."

Treatments for macular degeneration are limited, especially the dry kind. People lose center vision and sight becomes blurry. Some have bleeding in the eye that Dr. Ross can see on scans. So what can you do to protect yourself? Tulane researchers found that natural blue light in the daytime is good for us, but at night it is not. So there are glasses that have a yellow tint to them that are supposed to block some of that blue light from screens. There are also ones with a special filters or coating.

Tulane medical students no longer hit the books all night, they hit the screens to study at all hours. One student said she uses an app called f.lux. It goes by the sun in your location. so the screen color slowly and continuously changes with sunrise and sunset.

"Mainly my eyes get less tired, less itchy. I'm able to use my screen for longer before my eyes get super watery, and I'm physically forced to take a break," said Saritha Beauchamp a first year medical student at Tulane.

"I have anti-reflective coating, but I am a big believer in the filters," said Dr. Metzinger.

"Do these filters really make a difference? I mean, again the jury's still going to be out because we need controlled clinical trials. Look, so I'm a retina specialist and I use this every night," said Dr. Ross about his yellow filter built into his phone.

Dr. Ross says cataracts are nature's natural protection from the high energy blue light.

"As you look at van Gogh's paintings, as he got older, they got more and more yellow because he was developing cataracts," said Dr. Ross.

Now some doctors are replacing cataracts with yellow tinted lens when they remove them in surgery. But with all the filters and glasses on the market, there is a way that gives 100 percent protection from blue light screen exposure.

"I'm a big believer in having the kids stop using electronics a least an hour before bedtime, because you hear stories about kids that stay up all night in bed, looking at that screen, and then their behaviors are off their, their sleep patterns are off, and then it affects their school work," said Dr. Metzinger.

"We won't have the answer yet for many, many years until these young kids that have this high blue light exposure, get older and into the age range of macular degeneration, but I definitely think it's a concern," said Dr. Ross.

Even with filters and special glasses for blue light, doctors remind us that any light as it gets later into the night, stops the production of cancer-protecting hormones.

Meg Farris can be reached at mfarris@wwltv.com