Does the size of the eye increase as we develop from the stage the complete eye first forms to infancy and then to adulthood ?
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2 Answers
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First of all, I should quote the sentence from the MOST reliable ophthalmology sourcing in the world - American Academy of Ophthalmology:
Section 11 - "Lens and Cataract"
"The equatorial diameter of the unfixed human lens measures 2 mm at 12 weeks and 6 mm at 35 weeks. Both the growth and the maturation of lenticular fibers continue throughout life." The antero-posterior dimensions of the lens enlarge from 3 mm at infancy to 6 and even more in adult years.
"The lens continues to grow throughout life (page 7 the same source)
Secondly, the growth of the eye continues after birth - at the beginning the growth is fast and later the growth is much slower but still - there is GROWTH of the eye after the birth.
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$\begingroup$ @llan Thanks! If I assume that growth does continue, then how is new vitreous humor made ? Is the growth of the eye, after birth, so negligible that there is no need to add new vitreous humor ? $\endgroup$– biogirlApr 15, 2014 at 9:00
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$\begingroup$ @biogirl the vitreous is jelly-like substance with connective tissue as a skeleton. However, it is 99% water, thus to expand vitreous the ciliary body just filtrated more water. Actually with age vitreous becomes even more fluidic which causes specific to this processes, like Posterior Vitreous Detachment. $\endgroup$– IlanApr 15, 2014 at 9:05
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$\begingroup$ @llan The ciliary body makes more AQUEOUS humor not vitreous. I have read that NO new vitreous humor is made, it is present in fixed amounts. $\endgroup$– biogirlApr 15, 2014 at 10:51
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$\begingroup$ @biogirl check out what is happen after vitrectomy... what replaces the vitreous? $\endgroup$– IlanApr 15, 2014 at 10:53
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$\begingroup$ @llan Interesting question ! Though I don't know how that is replenished I can quote two lines from wikipedia which furthers the mystery - It is produced by cells in the non-pigmented portion of the ciliary body deriven from embryonic mesenchyme cells which then degenerate after birth and Unlike the fluid in the frontal parts of the eye (aqueous humour) which is continuously replenished, the gel in the vitreous chamber is stagnant. Therefore, if blood, cells or other byproducts of inflammation get into the vitreous, they will remain there unless removed surgically. $\endgroup$– biogirlApr 15, 2014 at 11:08
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No. In fact the lens of the eye, which is nearly optically perfect in humans, does not change or grow after it is fully formed around week 26 of gestation. Interestingly this is why one of the cues for identifying young children is having small faces with large eyes. This also the case for puppies and cats and other animals, who are mostly cuter when they are small with large eyes.
This doesn't apply to compound eyes though.
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$\begingroup$ Hi Ilan that comment comes across as quite terse, even rude. Such behaviour is not conducive to good discussions on this website and I recommend using constructive criticism in future if you have an issue with an answer. For example, your post is equally without citation regarding growth of the eye (not lens). Let's try to get along. $\endgroup$– user560Apr 16, 2014 at 19:30
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$\begingroup$ Your first link doesn't say anything other than when the eye forms initially. Your second link has a paragraph that starts out with "The lens continues to grow after birth..." Neither support your answer. $\endgroup$– NathanSep 28, 2015 at 20:32
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$\begingroup$ @shigeta I think you are wrong in saying that eyes don't grow after birth, see the following source : aao.org/eye-health/ask-ophthalmologist-q/… $\endgroup$– JM97Feb 27, 2017 at 15:53