From newborns to the elderly, people around the world are treated everyday using technology rooted in optics and photonics.
By harnessing the power of light to understand and heal disease, we are able to continue to develop new ways to improve people’s lives. In this chapter of The Healing Power of Light, we focus on neonatal jaundice as a simple case of how light can help us to see and treat disease in the most vulnerable infants.
Three out of five infants have neonatal jaundice within the first month of life, a condition caused by high levels of bilirubin in the blood. Bilirubin is a chemical naturally produced in the body as red blood cells breakdown; this product is toxic to brain cells and can cause permanent damage if levels are too high. Normally the liver breaks down bilirubin, however the infant liver may be underdeveloped in which case they need help to break it down.
Diagnosing Neonatal Jaundice:
Bilirubin has yellow pigmentation, which can cause the infant’s skin and eyes to have a yellow hue. Because of this coloring, light can be used to test if too much bilirubin is present by simply measuring how light reflects off of the infant’s skin. Four major features impact how light will reflect from infant skin: melanin, hemoglobin, bilirubin, and the age of the skin. The first three contributors absorb light of different colors, so each can be measured using different colors of light. Finally, the infant’s age is known, so combining this information with the reflected light gives clinicians a way to measure the concentration of bilirubin for any infant by simply shining light on the baby’s skin.
Accidental discovery of light therapy:
Exposing infants to sunlight has been practiced for hundreds of years; however, the exact reason that sunlight helped the babies was unknown. One warm summer day in the 1950s at the premature unit at Rochford General Hospital, Essex, Sister J Ward brought a premature infant outside. Upon returning to the unit, the baby was a pale yellow except for a small bright yellow section which had been covered up by the baby’s sheet. The nurse suggested it had been caused by the sun, but this suggestion was not taken very seriously.
Not long after this incident, a tube of blood from an infant with severe jaundice was placed on a windowsill before being taken to the lab for analysis. After sitting by the window, the sample measurements were well below the expected level: 13-14 mg/100 mL. Since it was obviously incorrect, a fresh blood sample was drawn and analyzed which read 24 mg/100 mL. The blood sitting on the windowsill was measured again, and read even lower, at 9 mg/100 mL. Finally, these two sets of findings caused researchers to investigate the effect of light on bilirubin. (Reference: Dobbs RH, Cremer RJ 1975 Phototherapy.)
Treating Neonatal Jaundice:
Research teams determined that irradiating bilirubin with blue light caused the bilirubin molecules to interact with oxygen. This causes the bilirubin molecules to change structure, creating a form of bilirubin that can be excreted naturally in the urine or bile, decreasing the infant’s toxic bilirubin levels.
The ideal wavelength to deliver treatment spans 460-490 nm, i.e. blue light, since this is the region in which bilirubin most highly absorbs light. Note that this does not include ultraviolet (UV) light, and therefore no harmful ionizing radiation is delivered to the neonate. Infants that are in need of treatment are commonly placed in special beds that have a blue light bulb that shines on them from above. Recently, blankets that are capable of delivering blue light therapy have been developed, allowing the infant to be with his/her mother during this important bonding time.
Even the simple act of shining light on the body has tremendous healing potential, and the detection and treatment of neonatal jaundice are two great examples of the use of light to improve patient care and our daily lives. The International Year of Light in 2015 will offer a fantastic opportunity to recognize the countless applications of light-based technologies in the medical field, and the role it will play in the future of healthcare.
- Maisels MJ, McDonagh AF. Phototherapy for Neonatal Jaundice. New England Journal of Medicine. 2008;358(9):920-8.
- Dobbs RH, Cremer RJ. Phototherapy. Arch Dis Child. 1975;50(11):833-6.
Christine is a Graduate Student at Vanderbilt University studying Biomedical Engineering. Specifically she is studying the use of Raman Spectroscopy, a light-based method that looks at the molecular makeup of a sample or tissue, for Women ‘s Health applications. Christine is the current President of the Vanderbilt SPIE Student Chapter, a professional organization focused on optics and photonics research and innovation, and enjoys participating in outreach aimed at teaching and exposing young students to light-based technologies and careers.
As a graduate student at Vanderbilt University, Isaac is investigating the use of light based technologies, like Raman spectroscopy, to improve disease diagnosis in clinical medicine. Additionally, Isaac is an active member and former leader of the Vanderbilt SPIE Student Chapter, through which he and his fellow students try to promote photonics and science outreach, sharing of ideas, and optics research and technologies for health care.