The Effect of Light and Dark Adaptation on the Eye

Our eyes are one of the special organs within the human body that are highly sensitive to almost everything it encounters and react as quickly as the mimosa plant reacts to touch. And so one who truly understands the complications of the eye could use it to diagnose so many pathologies as well as tell when there's something wrong in our bodies.

For example, a diabetic who has been studying him or herself could use how the vision responds to the glucose fluctuations in the body to easily tell that their glucose level may have spiked to dangerous levels when they begin to experience blurriness transiently perhaps after taking in unadvised foods.

Similar reactions occur with the eye when we are exposed to light in our environment and when there's inadequate light around. Optometrists or Ophthalmologists have studied this system as part of their care for the eye and could use this to assess the integrity of the brain function as well as the health of the optic nerve when they observe these reactions.

A delay in these reactions or an unexpected reaction could affirm a particular diagnosis as well as the point at possible diagnoses or differentials for your healthcare provider to investigate. This very simple reaction of the eye to light or darkness can even be used to diagnose some tumors in some cases, but let's leave the advanced techniques to the doctors and look at the simple ways we can protect ourselves by understanding these adaptive mechanisms.

So the eye is an organ that requires light to function, light activates the cells and allows something we call phototransduction to occur, thus, the conversion of light energy into electricity for the purposes of interpretation by the brain. But if you understand the principles governing energy or light, you would know that light is a powerful energy and could cause harm if not moderated.

And so the eye has natural mechanisms in place to protect itself from when things seem to get out of hand in the environment. This mechanism is done by the iris muscles, thus the sphincter papillae and the dilator muscles which work together to regulate the size of the pupil or the whole inside of your eye. It is through this whole that light can get into the eye and so the size of this whole automatically determines the amount of light that goes into the eye.

The cells of the retina are extremely sensitive and are susceptible to damage and so too much light could easily result in their death the death of these cells is irreversible and so their protection then becomes paramount to the body. This is why the lens also has its own properties to help reduce the number of ultraviolet rays that could actually pass through to get to the retina.

And so in the presence of extreme light, the pupil size reduces automatically whereas, in the presence of dimness or darkness, the pupil size opens up. It does this because it wants more light to be able to get into the eye so that vision could actually be possible. In the dim light, our vision normally becomes black and white instead of color, if there's enough illumination then it may range between the two (mesopic vision).

The cells responsible for black and white vision, thus the rods are more sensitive than the cones responsible for colored vision and could easily pick up stray rays even the tiniest bit in the environment to try and make the shape of objects in the dark, but their action ceases when there is enough light in the atmosphere for cones to work.

Understanding how the eye reacts to light and dark and why this is so now I believe I can go ahead to talk about some of our habits that we have been doing which are actually damaging to our eyes and giving us issues with our eyes without even realizing it. And hopefully, we could all learn to do better for ourselves and protect our eyes as a result.

Please do not wear dark shades or glasses with dark tints that have not been approved by your Optometrist in the sun. A lot of these dark shades or tints out there do not have UV protection and so what happens is that when we wear them and the dark cover comes over the eye, the eye starts to think that you are in dim light or illumination is poor and thus opens up the pupil to allow more light in.

Meanwhile, you are in the sun and the sun would be giving off ultraviolet radiation which could possibly harm your retinal cells, as the pupils open up instead of closing to protect the eye, the potential for damage increases. Now if these tints have 100% UV protection, they would be safe and make vision comfortable for those with low tolerance to high light levels. And so please let's always run our glasses by our Optometrist, or just to be on the safer side, avoid buying over-the-counter glasses.

The other thing is that we shouldn't be using our electronic gadgets in the dark. A similar thing as described for the sun and the dark shades also happen when we do this. Whiles tech producers are finding more innovative ways to combat computer vision syndrome and other ocular conditions that are coming up as a result of tech usage, we owe it to ourselves to do better and be better.

Smartphones as well as laptops and TVs tend to also emit radiations within the range of blue - wavelength, now continuous exposure to this is known to result in something we call computer vision syndrome which we have discussed here previously. When we work in the darkness, using our laptops and phones after turning the light off to sleep, we allow more of these radiations into the eye and thus accelerating the development of computer vision syndrome and dry eye conditions of the eye.

And so we owe it to ourselves and our eyes to stop these habits or behaviors, it may be fun for you but it is not fun to your eyes at all and eventually, you are going to feel the repercussions of your actions on your eyes and in your vision.

And so the next time your want to wear dark shades because the sun is scorching, remember what we have talked about today, if you are tempted to work in the darkness on your laptop or fon, remember what we have discussed here today and do better for yourself and your eyes. Always remember prevention is better than treatment.

Don't forget to prioritize your ocular health, have regular examinations, report any issues to your optometrists as soon as possible, avoid over-the-counter medication for the eye without proper examination, and always take good care of your eyes through proper dieting too. It is always a pleasure to serve you. Thanks for your time and I wish you a wonderful time.