A tool to measure haemoglobin – without drawing blood – has been created by scientists, using a phone.
The ground-breaking method uses pictures of a person’s eyelids to assess the levels.
Being able to perform one of the most common clinical lab tests without drawing blood could help reduce the need for in-person clinic visits.
That would make it easier to remotely monitor critical patients and improve care in countries with limited access to testing laboratories.
To take the measurement, the patient pulls down the inner eyelid to expose the small blood vessels underneath.
A medic then uses a smartphone app created by the scientists to take pictures of the eyelids.
Prof Young Kim, of Purdue University, Indiana, said: “Our new mobile health approach paves the way for bedside or remote testing of blood haemoglobin levels for detecting anaemia, acute kidney injury and haemorrhages, or for assessing blood disorders such as sickle cell anaemia.
“The Covid-19 pandemic has greatly increased awareness of the need for expanded mobile health.”
Professor Kim and colleagues from the University of Indianapolis, Vanderbilt University School of Medicine in the US and Moi University School of Medicine in Kenya used software to transform a smartphone camera into a hyperspectral imager.
The tool reliably measures haemoglobin levels – a measure of the oxygen-carrying capacity of blood – without the need for any hardware modifications or accessories.
A pilot clinical test showed that prediction errors for the smartphone technique were within five to ten per cent of those measured with clinical laboratory blood.