A mum posted this photo on Facebook. Then her friends noticed something odd...

This image was meant to be just a Facebook post from a proud mother, but it ended up being so much more.

It was the Facebook post that changed her daughter’s life.

A mother from the US had innocently put a photo of her three-year-old daughter on Facebook, expecting a few likes and maybe a nice comment or two.

She says she was proud because her daughter had done her own hair like a princess.

Two of her friends randomly looking through their news feed saw the picture of little Rylee and something did not look right.

Her left eye was glowing.

Tara Taylor from Tennessee had not really noticed the inconsistency. She just thought it was the flash reflecting in her daughter’s eye but these two friends knew it was something else.

“They said, ‘Hey, I’m sure it’s nothing’,” Taylor said to Memphis news outlet WREG. “‘But your daughter’s eye is glowing and you might want to have it checked out because it’s a sign there could be an issue with her eye.’”

After taking her daughter to her paediatrician, the three-year-old was diagnosed with Coats’ disease — a rare condition that can cause blindness or loss of vision.

Luckily, if caught early, this disease can be prevented.

Dr. Jorge Calzada with the Charles Retina Institute and Baptist Eye Clinic told WREG that the earlier they can treat children, the better.

“The significant problem we have with children is that a child won’t say, ‘Mommy, I can’t see out of my right eye.’ It is usually caught in an expected way. When a child recognizes he cannot see or the parent recognizes they cannot see, it’s often because they’ve lost vision in both eyes,” said Dr. Calzada.

For Tara Taylor, it was a complete surprise. Rylee had never had any trouble seeing.

“She didn’t sit close to the TV. She is actually in gymnastics and can walk on the balance beam,” she said.

Tara can’t quite believe how lucky they have been.

What is Coats’ disease?

Coats’ disease is a very rare congenital, non-hereditary eye disorder, causing full or partial blindness, characterized by abnormal development of blood vessels behind the retina.

Coats’ usually affects only one eye (unilateral) and occurs predominantly in young males 1/100,000.

Coats’ disease results in a gradual loss of vision.

The most common sign at presentation is leukocoria (abnormal white reflection of the retina).