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Do human eyes remain the same size from birth to death?

posted by Cathy Daub, CCE/CD (BWI)

 

The question is often asked if the human eyes grow in size after a baby is born, or do they stay the same size the rest of their lives?  Or maybe they grow so little that we don’t perceive them as growing? Actually, the answer is yes, babies eyes do grow but not very much compared to eyes of adults.  In fact, the dimensions differ among adults by only one or two millimeters.  Howard C Howland, Cornell neurobiologist, studied the sizes of eyes throughout stages of development and observed that “Human eyes grow rapidly in the womb and for the first three months after birth.” He goes on to say that this explains why babies are so adorable cute with disproportionately big eyes gazing out from those little round faces.

Those big eyes!  In a normal, physiological birth, the hormone adrenalin plays an interesting role.  It has the physical characteristic of helping a woman in labor to birth her baby.  But it also has a behavioral characteristic – that of dilating the baby’s eyes at the moment of birth so he/she can see his/her mother more clearly.  This is just another wonder of the workings of the human body.

From outward appearances, by three months, our eyes are the same size that they will ever be as the corneas have reached their full width.  But Howland notes that the front-to-back length will increase somewhat and then our eyes will begin to move more apart from each other as the head grows. According to the text General Ophthalmology (Vaughan, Asbury and Riordan-Eva, Appleton & Lange, Stamford, 1999), the size of the eyeball at birth averages 16.5 mm from front to back as compared to adults where it is 24.2 cm.

Stimuli from the external environment do change the axial length in human eyes.   At birth babies have “short” eyeballs and this makes them hyperopic.  A new mother is acutely aware that as her baby grows, he becomes more aware of the environment being able to see farther and this encourages him to use neck and head motions, thus strengthening those muscles, to follow objects at greater distances.   This is due to the eyeball adjusting in length for good eyesight.

Another interesting fact about eyes involves the collagen tissue.  It is fascinating to know that the collagen tissue in the human body forms a criss-cross pattern everywhere except one place – the eyes.  There, the collagen tissue forms parallel to each other allowing for transparency, which allows us to see.  This is so perfectly orchestrated by the master designer of the human body that we may see it as still another sign of the sacredness of birth, and of divinity.