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How does your brain turn light into vision?

Posted on 2015/03/05 at 3:00 pm by Galit G

Vision is arguably the most important sense that humans have, which is why it shouldn’t come as a surprise that so many people choose to undergo laser vision correction for their eyesight problems. In as little as a 10-minute painless procedure and a night of recovery, you could experience better vision than ever before. Given the precision of LASIK technology and the incredible importance many people place on good eyesight, it’s no wonder how laser vision correction has become one of the safest and most popular procedures today.

However, even though you probably prize good vision as much as the next guy, you might not know everything that goes into accurate and healthy eyesight. Maybe you skipped that day of elementary school or you’ve just forgotten how the captured light from your eyes is sent to the brain and converted into vision, but you should read on for a refresher course so you can know more about what makes your peepers tick and what you can do when things go wrong.

The eye as a camera
If you think that the eye is the most important part of healthy vision, you’re not totally wrong. Even though there’s an even more critical structure involved in the visual perception of the physical world, you couldn’t see a thing without properly functioning eyes.

Essentially an organic camera lens with some souped-up features, the eye is made up of several parts that serve to exclusively capture and focus light. This starts to happen at the outermost layer of the eye – the cornea. When light from lamps or other sources enters your eye or reflects off of other objects, this sturdy yet translucent lens passes light through the pupil – the black dot in the center of your eye. Then, light is bent and focused by the lens, which causes the rays to converge at a perfect point on the surface of the retina, the layer of photosensitive cells at the back of the eye.

This is where most laser vision correction procedures intervene. Refractive errors are conditions where the cornea, lens or a combination of other factors cause light to focus too far in front or behind the retina. LASIK procedures can reshape the inner lens of the eye without invasive incisions or harmful tools, which is one of the reasons why recoveries are so quick and complete.

The brain as the director
Hold on, now – you’ve only received half the story about how your eyes and brain convert light into vision. So far, your eye has done most of the work, but the second your cornea and lens focus rays onto the surface of the retina, that’s when things start to get interesting.

BrainHQ explained that the photosensitive-retinal cells automatically send electrical impulses through the optic nerve, the main neural highway between both of your eyes and the brain. These impulses travel through the nerve until they reach a region of the brain known as the lateral geniculate nucleus. While the LGN might sound science-y and imposing, it’s essentially just a junction for your brain to split electrical signals from your eyes into two categories – one maps color and detail, while the other categorizes contrast and motion.

Once these signals are split, BrainHQ then explained that the electrical impulses are shipped off to the primary visual cortex known as V1, which is located near the back of the brain. Interestingly, brain cells in V1 have a one-to-one spatial correlation with cells in the retina. This means that when a certain area of the retina is activated by a ray of light, its corresponding V1 cell lights up, too. Because of this organization, the brain can discern the horizontal and vertical position of objects in your field of vision. By comparing the differences in the signals from your two eyes, it can also calculate depth.

The learning eye
Just as your vision can improve or worsen with time, your brain also needs some time right after you’re born to figure out what to make of all this visual information. The U.S. Department of Health and Human Services explained that for the first few years, infants’ V1 regions aren’t as tightly organized as they are later in life. This means that babies might have trouble tracking objects in motion, but through repeated mistakes, the brain actually prunes the inaccurate neural connections to leave nothing but a functional V1 region in its place.

There’s a lot more that the brain does to provide you with a picture of the physical world, but those are the basics. If it seems like a delicate balance that keeps everything in check, you’re probably right. That’s why you shouldn’t hesitate to contact your local LASIK MD clinic as soon as possible to see what they can do for you and your vision.

Do you have a question about LASIK? Ask one of our experts!

Also available in/Également disponible en : French

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