An old wives’ tale says that people’s eyes stay the same size from the day they’re born. Of course, that isn’t true. In fact, the length of a newborn’s eye is only about 16.5mm, while adult eyes are closer to 24mm.1 The more microscopic structures of the eye grow too. As we age, macular vascular density and perfusion density continuously increase, a new study shows.2 The research into children’s eyes shows that, while the fovea avascular zone (FAZ) area and perimeter did not change, the microstructure of FAZ pruned and tended to form a smooth and regular avascular area during development.2
A team of researchers used OCT-angiography (OCT-A) to study the eyes of 333 healthy children between four and 16 years old. In particular, they narrowed in on a 3x3mm area centered on the macular region. They measured the subjects’ vascular density, perfusion density, FAZ area, FAZ perimeter and FAZ acircularity index (AI), while adjusting for axial length, and then compared outcomes between age groups.
They found that both macular vascular density and perfusion density were larger in the older age groups, showing that these increase with age. After adjusting for the spherical equivalent (SE) and axial length, macular vascular density was significantly associated with age. No factors were significantly correlated with the perfusion density after adjusted for the age, SE or axial length. However, the FAZ area and perimeter remained constant among all the groups, while the AI of FAZ in the four- to seven-year-old group was smaller than in a group between the ages of 13 and 16.
Of note, the younger subjects had significantly higher rates of inconsecutive vessels branched towards the macular center and vascular loops contributing to an irregularly shaped FAZ.
So, eyes continue to grow, both in ways that can be seen unaided by instrumentation and through the microvasculature that can only be observed with high-tech equipment. So much for old wives’ tales.
1. American Academy of Ophthalmology. Is it true that we are born with our eyeballs already full grown? www.aao.org/eye-health/ask-ophthalmologist-q/are-eyes-fully-grown-at-birth. March 11, 2014. Accessed May 22, 2020.
2. Li S, Yang X, Li M. The developmental changes of retinal microvasculature in children: a quantitative analysis using OCT angiography. May 12, 2020. [Epub ahead of print].