Eye Health

Dr Thanh-Tam Pham - 18/07/2021

According to Dr Huberman, a professor of Neurobiology and Ophthalmology at Stanford University, most people do not appreciate that the eyes are actually two pieces of the brain outside the skull so they are part of the central nervous system. They can registerevents in the environment at a distance in order to provide information to adjust the overall state of alertness of the brain and body and of mood as well.Vision gives the ability to perceive objects, shapes, sizes,colourswith distance and depth.

When light hit the retina, a light sensitive membrane, special cells called photoreceptors turn the light into electrical signals. There are 2 types of photoreceptors in humans:

-Rods are responsible for vision at low light

-Cones are active at higher light leveland capable of colour vision and responsible for high spatial acuity.Humans have 3 different cones for red, green and blue vision.The central fovea is exclusively populated by cones.

These electrical signals travel from the retina through the retinal ganglion cells of the optic nerve to the brain.

The eyes take the light information and send the signals to the brain in a form that the brain can understand. We do not see anything directly, the brain tries to compare the incoming informationwith the things around it and makes a guess based on the pattern of electrical signals received. Other animals do not see the same colour that we see depending on how many cones that they have( 1,2 or 3), so their world looks different than what we see.What we experience in the outside world is limited by what wavelengths of light we can see. The brain also gives us the sense of depth as the things at a close distance are bigger than the things that are further away.

The brain uses 40 to 50% of real estate for vision.

We have eyes to communicate the time of the day to our brain. The melanopsin retinal ganglion cellscommunicate and signal the brain about the time whether early day or late in the day. It responds best when there is a contrast between the yellow and blue contrast of the sunlight. We need to anchor ourselves in time at the biological level where the sun is. It helps to set the circadian rhythm, promotes eye health, wakefulness, dopamine levels, pain threshold, metabolism and mood.We need to get sunlight especially the blue lightearly in the day. People with low vision or no vision still have those melanopsin cells to signal the time of the day to the brain.

There are many studies to prevent myopia. We need to get sunlight 2 hours a day and it can prevent myopia. Ideally, we all get 2 hours outdoor even though there is cloud. A study looking at students who spent 11 hours outdoor a week in many different schools (Ophthalmology Journal in 2018,) found that the sunlight exposure could offset the development of myopia.The probable mechanism is that the melanopsin cells have connection with the ciliary body to move the lens, and by being activated by sunlight,they increase blood supply and growth hormone to the accommodation system.

Staying indoors and looking closed most of the time can cause visual defects.

If we can hold visual focus, we can hold mental focus. Mental and physical pursuits are grounded in visual focus.

In accommodation, the ciliary bodies relax and the lenses flatten out when we look far away. When we look closed the lenses get thicker to bring light onto the retina and not in front or behind. When we look closed most of the time, we are not allowing the muscles to relax and we are reshaping the neuronal circuit and get the accommodation system to get stuck.

Every 30 min of looking closed, it is beneficial to try to relax the eyes to look far away. Every 90 min, it would be good to go out getting sunlight and look at the horizonfor 10 min and have a panoramic vision. The epidemic of myopia can be dealt with by going out and look far away.

The optic flow happens when we move through space like walking, running or cycling, the images around us are passing by. Things are moving past our retina at varying speed depending on how fast we are moving and this stimulates a set of circuit in the brain and body for improving mood andhaving a relaxing and calmingeffects.

When we are tired, the eyelids are closed and the chin drops down, when we are alert, the eyes are opened wide and the chin is up. When we look up, it creates a wakefulness circuit in the brain. Therefore, when we are tired, try to look up toward the ceilingfor 10-15 sec. If we work with computer all day, put the screen at or above eye level and this will increase the alertness rather then look down.

Children that sleep in the room with nightlight at night, were found to have an increased risk of developing myopia comparing to children who sleep in a dark room. Low intensitylight can enter the close eyelids in the middle of night and especially light exposure from 10pm to 4am is detrimental to mood and learning.

Most colour blind people have red green colour blind that is they are lacking the red photo pigment cones. They have green cones but the brain cannot do the comparison between red and green and they will see red as brown.They can differentiate majentabetter than red.

Monochromatsare very rare and they see the world in black and white.

Protocols to improve the vision: we need to train our vision as we would for other muscles in the body.

When we look at the horizon, the eyes are relaxed. At least 10 min a day seeing the horizon in the sunlight without sunglasses and not through the window screen is beneficial.

Smooth pursuit is the ability to tract a moving object smoothly through space such as following a sport game, a car/object moving, children playing… Spending5-10 minutes each day or 3 times a week in smooth pursuit training will keep the extraocular muscles strong.

Near far training 2-3 minutesevery 2nd day. This technique is used in post-concussion training to repair the vision and the brain ability to make sense of the world.

Age macular degeneration. Flashing red light 2min a day early in the day before noon may offset the development of macular degeneration by enhancing mitochondrial function but this technique is still in the early days and needs more research.

Poor eyesight may be due to dry eyes especially when working at the computer.Blinking for 5-15secwill help.

Binocular vision and lazy eyes. The two eyes are competing for real estate in the brain.The young brain of children up to 7 years old (or maybe to 12) is very vulnerable to asymmetrical or imbalance in vision. Even by covering 1 eye for a short period of time can affect thevision and the child may lost the vision of that eye. We need to correct strabismus in children, cataract or visual defects such as long sighted or short sighted in one eye early in life. When a child has a lazy eye, the good eye can be coveredfor the lazy eye to recover.

When you cover both eyes, hallucination can arise when the portion of the brain is understimulated and the brain started to compensate by making guesses of what is out there. This can happen when people spend some time in a dark cave.

If use glasses that over correcting the visual acuity, the eyes get weaker

Food and supplements

Light gets onto the retina and is transformed into electrical information- this process needs vit A. Dark coloured vegetables eaten near their raw forms are a good source of vitamin A.

Luteinin in raw egg yolk – some evidence shows that lutein increases macular pigment density and improves vision and it can offset the macular degeneration in people withmoderate or severe degeneration. If normal vision or mild degeneration, it does not help.

Nutrients found in the red pink pigment of seafood (such as shrimp) appear to increase ocular bloodblood.

Zeaxanthin, Astaxanthin were shown to offset some macular degeneration and increase ocular blood flow

Blood flow is critical to the eyes so have a good cardiovascular system will support the eyesight by supplying oxygen, nutrients to the eyes and the brain to support vision over time.


Huberman Lab podcast- Improve your eyesight.