Pilot Night Vision

Welcome back! I'm Jacob and this video covers a pilot's night vision. Not necessarily Night Vision Goggles (NVG's) or thermal sensors but your actual eyes and their ability to see at night. Be sure to hit like and subscribe and we'll get started.

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Vision is different in the daytime than it is at night, obviously, and this is at the physiological level. That's because your eyes are made up of cone cells and rod cells. These are the photoreceptors that allow you to see. Cone cells are for high intensity light conditions and give you high visual acuity in sharp image interpretation as well as color vision. Rod cells are for low intensity light conditions. They are 1,000 times more sensitive than cone cells to light and a give you your natural "night vision." So how do these cells work together? It depends on the type of vision used.

Scotopic vision is during eh daylight or high level of artificial light present. The cones are primarily responsible for vision here because the rhodopsin (in the rods) is bleached out. More on rhodopsin later. In photopic vision you can see sharp images and distinguish color because the cone cells. Mesopic vision is generally associated with dawn, dusk, and full moonlight. Instead of just cone cells, your vision is relying on a blend of cone and rod cells. Visual acuity and color perception from the cones starts to go down and your rods start to pick up the slack. This leads into Scotopic vision which is little to no light present. Cones are ineffective and detail is lost. Visual acuity can degrade from 20/20 vision to 20/200 or less. Color vision is lost. Vision is severely degraded but is not lost thanks to your rod cells. Your rod cells contain rhodopsin which is a photochemical that increases when illumination decreases in the process of dark adaption. So simply put, cone cells allow you to see in the day while rod cells allow you to see at night.

On the topic of dark adaption, this is when your eyes adjust to low level light conditions. It's like when you walk inside a dark room from the bright day outside. At first, you don't see much of anything. Then over time you see dim outlines and finally the room has detail. This is the process of switching from photopic to scotopic vision. The rhodopsin in your rods was bleached out in the sun. When you first walked inside you couldn't see because 1) there wasn't enough light for your cone cells to pick up and 2) the rods did not have enough time to build rhodopsin. As the rods saturated with rhodopsin, you could see. Thats dark adaption and here are some facts about it:
-Generally takes 30-45 minutes
-Rods become 10,000 more sensitive in the process
-Lower intensity light to start reduces time required to dark adapt
-Brief exposure to bright lights can reduce/reset your dark adaption depending on intensity and severity
-NVG's/thermal sensors display a type of photopic vision and do partially reduce dark adaption. But the light intensity is so low that it generally only takes 2-5 minutes to regain dark adaption.

So how do you protect your dark adaption/night vision?
-Wear sunglasses. Exposure to bright, unfiltered sunlight for 2-5 hours a day can affect how long it takes and how much you can dark adapt.
-Reduce office lighting. If on night shift, keep office lights low in case you have to launch quickly. Lower intensity lights reduce time required to dark adapt compared to high intensity lights.
-Minimize airfield/cockpit lighting. See if the aircraft can be positioned to a part of the airfield with less lights. Fly with cockpit lighting at the lowest usable level.
-Eat Vitamin A rich foods. The body needs vitamin A to produce rhodopsin. If you're deficient this vitamin, your night vision will suffer. Eat foods like eggs, butter, cheese, leafy greens, etc.
-Lastly, if flying above 4000' pressure altitude, bring supplemental oxygen. As I mentioned in my hypoxia video (Here:    • Hypoxia in Helicopter Pilots  ) reduced oxygen can degrade your night vision.

That's about all the time I have for this video. If you plan on flying at night, make sure you're doing what you should to give yourself the best night vision you can. Be sure to hit like and subscribe. Thanks for watching. As always, I'm Jacob. Safe flying.