The most utilized sense in a lifetime is probably the view that enables us to communicate with the world through eyes.
Sight is a sense almost essential; its loss creates a serious disability. It is therefore important to preserve it at best.
Melatonin is a molecule produced by human body and plants, which modulates the visual function, improving it.
How does melatonin modulate visual function?
Melatonin is a hormone that regulates the circadian rhythm, or sleep/wake rhythm of most animals, including humans. It has a number of effects especially on the brain, but also directly on the eyes.
The release of melatonin from the pineal gland in the brain occurs in more or less large quantity according to ambient light condition detected by eyes and consequently it regulates the circadian rhythm.
Recent preclinical studies conducted on mice, which produce melatonin as well as human beings, would seem to show that the hormone has also a direct responsibility on sight modulation.
However, some mice are insensitive to melatonin due to genetic reasons and as a result of a specific receptor.
Researchers formed and compared two groups of mice. One group was sensitive to melatonin and the other not. After applying both the same amount of hormone, they had the vision ability of these animals. They discovered that mice sensitive to melatonin, after an electrophysiology testing (similar to the electrocardiogram, but made on the eye and not on the heart), had a more effective response to stimuli of light: in practice, they could see well, especially in the dark.
This is understandable in the light of the scientific knowledge of natural melatonin cycle: it is produced in low light, and though it should stimulate sleep, it is useful to be able to see well in that condition. Melatonin receptors cause retinal cells, especially cones, to increase their sensitivity to light stimulus.
The increase in sensitivity normally occurs in the eye (just turn off the light to no longer see anything but, after a few minutes, the eye becomes more sensitive to the lack of light and the view opens up), but melatonin enhances this ability. It is useful for improving visual ability.
For which visual disturbances is useful melatonin?
Melatonin is beneficial in all disorders of the retina, while it has no effect on iris problems, crystalline lens and cornea. It can also be hired for night vision, poor colours perception (except colorblindness because is a genetic condition), the lack of sensitivity to light, the retinal degenerations, retinal atrophy and, in general, and any condition regarding the light sensitivity.
Myopia and presbyopia will not derive any benefit from the integration of melatonin as well as conjunctivitis or corneal ulcers that lead to leading to vision problem.
Melatonin, therefore, is not only useful for the regulation of circadian rhythm, in fact it can also be used to support medical therapy in a series of eye diseases.