Study in mice, led by experts at Cincinnati
Children's, shows that lighting conditions can change how newborn
eyes develop
CINCINNATI, Aug. 14,
2024 /PRNewswire/ -- Researchers and clinicians have
known for years that people born very prematurely often develop
eyesight problems later in life.
Many of these problems have been linked to a condition called
retinopathy of prematurity, in which vision is damaged by excess
blood vessel growth within the eye. Now a study—in mice—from the
Science of Light Center at Cincinnati Children's reports that
preterm birth also can affect eye development through changes in
the eye's supply of photoreceptor cells called rods.
Findings were published online Aug. 13,
2024, in Developmental Cell.
"Our work highlights that the lighting environment is crucial
for rod abundance in early postnatal mouse development," says the
study's lead author Shane D'Souza,
PhD. "If they develop entirely in the dark, their eyes wind up with
more rods than if they develop in a normal day/night light
cycle."
Rods are tall, cylindrically shaped photoreceptor cells in the
retina that help the eye see in low light and at night. Rods are
500 to 1,000 times more sensitive to light than cones, the eye's
other major form of light-sensing cell.
For years, scientists believed that differences in cone-rod
light sensitivity most likely reflected "hard-wired" genetic
variations among individuals. However, this study shows that
external lighting conditions play a direct and large role in
driving how many rods form as the eye matures. This finding has
potentially significant implications for how newborns are cared for
in neonatal intensive care units and for future studies involving
mice.
"Many intensive care units have lighting standards that vary
according to infant age. They can range from no lighting at all, to
extremely dim (1 lux), to bright (600 lux)," D'Souza says.
"Meanwhile, when a premature infant needs a procedure, they can be
exposed to very bright lights that are needed for the caregivers to
see. These changes in lighting conditions could affect how many
rods the eye develops and this could have long term effects on
vision."
Richard Lang, PhD, director of
the Science of Light Center and senior author on the new study, has
devoted decades to studying the surprising ways light affects body
development and homeostasis. In 2021, based on his team's research,
Cincinnati Children's installed a programmable full-spectrum
lighting system in its upgraded NICU area and developed portable
units that can change lighting in other select locations. The novel
system can allow indoor spaces to mimic natural cycles of outdoor
sunlight, including seasonal and daily patterns. Specific
wavelengths of light also can be adjusted to explore potential
light therapy applications.
"Moving forward, we are looking at ways to prevent rod death in
our mouse models by using spectrally tuned lighting," D'Souza says.
"If we can implement lighting as an intervention strategy, we could
use the lighting systems in our own NICU to potentially reduce the
impact on the retinas of premature infants while also providing
effective lighting for our clinical teams."
Meanwhile, the new findings suggest that future studies
assessing eye development will need to be executed with
standardized lighting that satisfies the needs of the rod
development pathway.
"This study adds a new dimension to our ever-growing
understanding of how the murine eye develops, even prior to the
eyelids opening," D'Souza says. "There is immense variation in
lighting across institutions and even within institutions, or even
within a single rack of cages. Lighting intensity can vary 100-fold
between the bottom and the top of a rack. This variability can
impact studies of the visual system, so it may be important to
begin implementing environmental lighting standards for mouse rooms
or cages."
About the study
In addition to D'Souza and Lang, Cincinnati Children's
co-authors on this study included Brian
Upton, MD, PhD, Gowri Nayak,
PhD, Kassidy Grover, Minh-Thanh Nguyen, PhD, and Yueh-Chiang Hu, PhD. Experts from the
University of Washington, George Washington University, and the University of Alabama at Birmingham also
contributed.
Funding sources for this work included grants from the National
Institutes of Health (R01s EY032029, EY032752, EY032566, EY034456,
GM15264, R01 EY025555, T32NS007453, R24HD000836, and P30EY003039),
the Goldman Chair of the Abrahamson Pediatric Eye Institute at
Cincinnati Children's, the Damon Runyon Cancer Research Foundation,
the Albert J. Ryan Fellowship, and the Hanna H. Gray Fellows
Program.
Read more
Spectral Lighting: Novel Science Leads to Innovative NICU
Design
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SOURCE Cincinnati Children's Hospital Medical Center