Kitasato University Hospital researchers in Japan found that patients with smaller eye pupils were twice as likely to die from heart failure.

Meanwhile, 47 per cent of those with small pupils were readmitted to hospital, compared with just 28 per cent of those with large pupils.

Study author Dr Kohei Nozaki, of Kitasato University Hospital in Japan, said: ‘Our results suggest that pupil area is a novel way to identify heart patients at elevated risk of death or hospital readmission.