One is occasionally struck by a basic scientific question that has been curiously neglected for study. Sometimes the question is neglected because everyone takes a presumed answer for granted. Sometimes nobody feels the question is of sufficient importance to warrant investigation. As an example of such a question, consider the networks of capillaries in the retina and the choriocapillaris. Are they invariant over time; ie, is the pattern of retinal and choroidal capillaries that one has at 20 years of age identical to the pattern 50 years later? Or do those networks remodel themselves over time the way the trabecular structures of bones, the synaptic connections in brains, and the distribution of adipose tissues in the body are continually revised? The presumption is that the capillary beds in the retina and choroid do not change as long as the eye is healthy. There is certainly no variation over time in the pattern of the precapillary arterioles and postcapillary venules in the retina observed in standard fundus photographs because those patterns can be used to uniquely identify people regardless of their age. It is hard to imagine that the intervening retinal capillaries remodel themselves. For the normal choriocapillaris, we truly do not know. One might definitively learn the answer by examining high-resolution fluorescein or indocyanine green angiograms in people over time or looking for vascular endothelial cells that are in the cell cycle (eg, expressing Ki67) in histologic sections. Such studies are either unpublished or are so deeply buried in the internet that a superficial Google search fails to find them.
Dryja TP. Early Insight Into Neovascular Age-Related Macular Degeneration. JAMA Ophthalmol. 2016;134(11):1281-1282. doi:10.1001/jamaophthalmol.2016.3031