Abstract

Retinal vessels of newborn and premature infants were photographed under conditions of increasing arterial oxygen tension and the changes in vessel diameter were measured.

In 6 infants studied, there was a consistent pattern of vasoconstriction with rise in P_ao₂.

The reduction in calibre could be measured, but was not detectable by viewing the retina, unless photographs taken at low and high P_ao₂ were viewed side by side. Frank retinal vasospasm did not occur even at a P_ao₂ of 250 mm. Hg.

It was concluded that ophthalmoscopy did not provide an alternative to direct frequent measurement of P_ao₂ in premature infants receiving oxygen therapy.