Standing out as one child in a large family is always a challenge. Standing out as one of quintuplets is an even bigger challenge. And when you are one of the only all-girl sets of quintuplets in America? It's easy to get lost in the crowd.

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Hazel Grace Busby, who is one of the quints on the TLC show Outdaughtered manages to be unique among her sisters because of her cute pink glasses and her red hair. The five-year-old is the only one of her sister — five total when you count big sits Blayke who is nine years old —to need glasses. And while a kid wearing glasses is far from uncommon, the reason for Hazel's prescription lenses is a little different. She as born with a condition called nystagmus that causes uncontrolled eye movements.

What is nystagmus, Hazel Busby's eye condition on Outdaughtered? 

She was diagnosed with nystagmus as a baby.

When Hazel was still very little her parents noticed that her eyes moved in an unusual way. Mom Danielle sometimes describes it as "wobbling" and it's an uncontrolled motion. The condition is called nystagmus and, while rare, not unheard of. In cases like Hazel's, the eyes most often swing from side-to-side and the result is that a person has trouble focusing on objects. Hazel, as is typical for the condition, had to hold her head at an angle to be able to see things clearly. 

Sometimes it's a sign of other health issues.

The condition can also be associated with other problems such as albinism, congenital absence of the iris (the colored part of the eye), underdeveloped optic nerves, and congenital cataract. But Hazel doesn't appear to have any of those conditions.  

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She underwent surgery when she was a baby. 

One way of treating nystagmus is having surgery to adjust the muscles around the eye to better stabilize the eyes. This treatment allows a person to stop compensation for the condition by turning their head. The Busbys opted for this treatment for Hazel, which was documented on the show. Danielle Busby explained on the show that the surgery wasn't intended to address Hazel's vision. "It's more so to correct the placement of where her eye goes to focus better so she doesn't have to turn her neck, which is a huge deal," she told the cameras.

Hazle has worn glasses since she was a toddler.

The surgery worked, but it isn't the end of the story.

The surgery did what they intended it to do and Hazel can more easily focus on objects without having to turn her head. But she has other vision issues to contend with now. She has astigmatism in one and has far-sightedness as well. That's all correctable with glasses, however, so she wears adorable pink frames all the time. There may be a need for more treatment in the future. "It's inevitable that one day she'll have another [surgery]," Danielle said. "So we visit her eye doctors every couple months."

Hazel is developing typically in all other ways.

Because all the quints were born very premature, the Busby family had concerns that their development might be affected so they had all the girls tested. Hazel, in particular, lagged behind her sisters the earliest years. But once she could see more clearly after the surgery and the glasses, she caught up and is now happily attending preschool with her sisters. (Riley is the quint who's a grade ahead in Kindergarten.) On the family blog, her parents describe her as Miss Independent and say "she is super-social and confident."

Her future vision issues are in question.

One of the things about nystagmus is that it's unpredictable. There's no way to know for sure how it will affect a person over the course of their lifetime. There is also no cure, so Hazel will always have to contend with the effects of the condition. In an Instagram post for Nystagmus Awareness day in 2019, the parents talked about what it might mean for Hazel in the future. "This condition that causes Hazel’s eyes to wobble has no cure. There are only treatments for the symptoms that comes along with it. We have no idea how far-reaching her condition will affect her later in life. We have heard it all; from being considered legally blind and not being able to drive a car, to just needing glasses and may struggle to focus and everything in between." 

"We are so thankful for her amazing attitude and how she takes every difficulty in stride," the post continues. "Here is to hoping that one day, a doctor somewhere can crack the code on this rare condition."

Hazel Busby in 2019.

Outdaughtered airs on TLC on Tuesday nights.

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Rebekah Kuschmider has been writing about celebrities, pop culture, entertainment, and politics since 2010. She is the creator of the blog FeminXer and she is a cohost of the weekly podcast The More Perfect Union.