You can use your smartphone to determine if your child has a deadly form of cancer. Here’s how.

Retinoblastoma is a dangerous form of cancer.

While retinoblastoma is a rare form of cancer, it’s actually the most common eye cancer that affects children. It generally develops in children under 4 years old, and 18 months is the average age of diagnosis.

The good news is that when it’s caught early, retinoblastoma is highly treatable. Early detection can save a child’s vision — and their life because when retinoblastoma advances and spreads, it can be deadly.

You can easily check to see if your child has it.

Retinoblastoma can often be detected with a photo because the flash can cause the pupil to turn white if it’s present.

So pull out your cellphone, turn on the flash, and snap a photo of your kiddo. It’s that simple. If you see white in one or both of your child’s pupils unexplained by lighting conditions — especially if you’ve noticed other retinoblastoma symptoms like squinting or lazy eye, redness or swelling not due to infection, a change in iris color, or vision loss — schedule an appointment with their doctor immediately.

Share this with your friends and family members who have kids. We all know we parents take excessive photos of our little ones, so let’s make sure we all realize that in addition to preserving memories, we could save their vision — or their lives!