According to the Childhood Eye Cancer Trust (CHECT), the flash from the smartphone camera can easily spot retinoblastoma, a rare type of aggressive eye cancer that almost exclusively affects young children.
The disease develops as a tumour in the retina.
Using the smartphone, the team at the charity has saved the life of British mother Eilise Somers' four-month-old daughter Arwen who was suffering from retinoblastoma, The Verge reported.
Since the operation, Arwen has made a full recovery.
"Our hope is that our research will mean no child ever has to experience the trauma of losing their eye, their sight or their life through eye cancer," CHECT chief executive Joy Felgate was quoted as saying.
Children who have the disease often have a white glow around their pupils that shows up when photographed with a flash.
When a tumour grows inside a child's eye, it can reflect back as a white pupil in flash photos and if spotted early, it could save a child's vision, eyes and life.
As a diagnostic tool, smartphone cameras are so effective that CHECT ran an ad campaign last year.
They put up posters of children's eyes that flashed white when photographed thanks to the use of reflective ink.
CHECT said that with the average person spending hours of their life staring at their phone screen, they should put the devices to better use to look for the eye disease.
According to doctors, spotting a white flash in a child's pupil is not a definitive diagnosis of retinoblastoma but it is always worth following up.