How well do we know our eyes? Perhaps not as well as most of us think, as myths about vision are - it seems - very popular.
So let's play a quiz. But don't be in a hurry to answer, as the eyes are highly complex organs.
The facts about some of the most common vision myths are summarized by ophthalmic surgeon and professor of ophthalmology at NYU Medical School, Dr. Anastasios-I.
Babies do not see when they are newborns
The truth is that they do see, they just do not have full visual ability to distinguish all colors, see equally clearly near and far, focus their eyes, move them accurately, etc. All these skills are acquired gradually as they grow older. At birth, for example, they have peripheral vision, but their central vision is not yet fully developed. Thus, on anything that is straight in front of them and at a close distance, they can focus easily after the first month of life. In addition, eyes reach their full size after puberty, as when we are born, they are two-thirds the size they will be when we become adults.
Eyes change colour in the first year of life
Neither yes nor no. When babies are born, they often look like they have light-colored eyes because their bodies don't yet produce enough melanin. Within the first 12 months of life, melanocytes have begun to produce this natural pigment in the body. The more melanin builds up in the iris of the eyes, the darker their colour becomes.
But this doesn't happen in all babies because not all babies produce the same amounts of melanin. Furthermore, babies born and left with blue eyes do not mean that they produce blue pigment. Their eye colour is due to the same natural phenomenon by which the sky turns blue: they cause sunlight to scatter so that more blue light is reflected at different angles.
We can improve our vision with eye exercises
Eye exercises do not improve or maintain vision. Nor do they reduce the need for glasses. Vision depends on many factors, none of which are particularly affected by eye exercises. What eye exercises can do is to give them a rest when, for example, they suffer fatigue from long hours of reading or writing on a computer.
They may improve their focus, but not their visual acuity. Similarly, exercises are useful when there are problems with the convergence of the eyes (e.g. strabismus). In such cases, the eyes do not cooperate well to focus on an object. Again, however, their benefits are for the eyes, not the vision.
Nothing happens if you stare at the sun for a while
Even for a short time, staring at the sun without proper eye protection risks causing uncomfortable damage to the delicate eye tissues. Even a glance at the bright sun is painful, which is why we instinctively half-close our eyes and turn our heads away.
If we force ourselves to look at the sun (or if we do so when it is cloudy and the sun is not very bright) we risk burning the retina of our eyes. This is located deep inside the eyes and has no pain receptors. So we will not immediately notice that the sun's rays have caused a burn at some point, destroying the light-sensitive cells (rods and cones) on it.
The consequence is that "blind spots" develop in the visual field (called scotomas), which can become perceptible after hours (or even days).
People who are colour blind see the world in black and white
Colour blindness usually develops in people born with partial or total absence of retinal cones. Cones are the light-sensitive cells in the eyes that allow us to distinguish between red, green and blue. Most people with colour blindness have difficulty distinguishing between shades of green and red, so they can only partially see colours (the condition is called deuteranopia and is the most common form of colour blindness).
The more severe form, in which everything is shown in shades of grey, is very rare. Another myth that accompanies colour blindness is that only boys have it. Although it is much more common in boys (it is estimated that one in 12 are born with some form of colour perception disorder), it can also occur in girls. Moreover, colour blindness is not always a congenital disorder.
It can also develop later in life as a result of disease, trauma or the toxic effects of drugs that damage the retina or optic nerve.
Vision loss is inevitable with age
Changes in vision are inevitable, but not only is vision loss unavoidable, but we can take steps from an early age to protect it. Most people, for example, develop presbyopia as they get older, but this does not take away vision.
On the contrary, cataracts and other eye diseases (e.g. age-related macular degeneration) can be prevented, treated or even delayed if they are detected early. This is why preventive vision screening is required every 1-2 years, especially after the age of 40, so that any problems can be diagnosed in time.
Eye transplantation can improve vision
It is not possible to transplant the whole eye because this complex organ is connected to the brain by the optic nerve, which consists of 1 million thin nerve fibres. When these fibres are cut, they cannot be reconnected. What is possible and practicable is corneal transplantation (keratoplasty). The cornea is the clear, outer layer of the eye. It may need to be transplanted if it becomes thicker or cloudy due to inflammation, disease (e.g. keratoconus), trauma (e.g. burns) or other causes.
"Corneal donation is one of the most moving aspects of human solidarity. As a corneal transplant surgeon in Greece and the US, with clinical training at Cornell and Harvard Universities and systematic teaching since 2010 at New York University, I have performed thousands of transplants and have experienced the incredible gift from the grieving family to the family that regains the miracle of sight," concludes Anastasios-I.
Source: in.gr
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