In the present results, definition of the avascular area,
deepening of the foveal depression by neuronal and Müller cell
migration, and maturation of the perifoveal plexus took place between
Fd105 and P3 week in the
Macaca monkey. In the human a
comparable period is 25 WG to P3 month.
25 Human infants
are at high risk of development of retinopathy of prematurity if
delivered before 28 WG.
50 Long-term follow-up studies
indicate that even when retinopathy is not present in the neonatal
period, premature infants of 31WG or less are at increased risk of
development of some form of ocular disorder, including myopia,
hypermetropia, strabismus, astigmatism, or poor visual
acuity.
50 51 52 53 54 The results of the present study suggest
that the astrocyte–vascular interactions that establish the human
perifoveal plexus occur during this vulnerable period, as do the
neuronal migrations that form the foveal depression and elevate cone
density.
4 28 Because perifoveal plexus development and
formation of the foveal depression appear interdependent, it seems
likely that the changes in retinal
P
o 2 experienced by
premature infants could affect these normal developmental interactions,
retarding growth of the perifoveal plexus at a time when the foveal
depression is beginning to form. This in turn may indirectly affect
neuronal displacements, resulting in subtle abnormalities that may
underlie the visual difficulties experienced by premature infants.
The authors thank the staffs of the Regional Primate Research
Center at the University of Washington and the Indonesian Primate
Center (Bogor, Java) for their critical role in obtaining this valuable
primate tissue; and Andra Erickson, Dan Possin, and Vera Terry for
technical assistance.