During pregnancy, a baby's eyes grow around a central seam, and after about seven weeks, that seam should close. When it doesn't, a coloboma forms. (Learn more)

Coloboma is a fancy word for gap, and it can affect almost any part of the eye, including the iris, the cornea, or the eyelid. (Learn more) 

The gap represents a weakness in the eye, and that can lead to other health issues, including glaucoma and retinal detachment. (Learn more) There's no treatment to seal up the fissure, but regular eye exams can help doctors spot associated issues before they steal your vision.

The amount of discomfort you'll feel due to coloboma depends on where it is and how large the gap is. It's not uncommon for people with this condition to deal with sun intolerance and low vision, but a few lifestyle changes can help you manage those problems. (Learn more)

coloboma

What Is Coloboma?

A coloboma is a gap in the structure of your eye. This term applies to almost any kind of cleft in the eye.

The National Eye Institute says a coloboma can form on the:

  • Eyelid. A part of the upper or lower lid is missing. This can look like a notch, or it can have a ragged edge.
  • Macula. This structure in the back of your eye is responsible for full-color vision. A macular coloboma refers to a hole in this vital structure. You won't be able to see this coloboma in a mirror, but your doctor will see it during an exam.
  • Optic nerve. This structure relays images from the eyes to the brain. An optic coloboma can hollow out the nerve. You won't be able to see this type of notch either, but your doctor can see it during an exam.
  • Lens. This part of the eye focuses light on the back of the eye. A coloboma here typically looks like a dip or a notch. You won't be able to see this gap.
  • Uvea. This front portion of the eye provides nutrition and gas exchange. A uveal coloboma can look like a notch in the colored part of the eye.

How Does It Develop?

A coloboma is a birth defect, and it's typically in place early in the pregnancy. There's nothing you can do to prevent your own, but if you have one, you might pass it along to your genetic ancestors.

During gestation, babies develop along a sort of fault line. Tissues grow on either side of that fissure, and at some point, they connect into a formed whole. The structures of the eye all develop this way, and when something interrupts the process, a hole remains. That hole is a coloboma.

The American Academy of Ophthalmology reports that this is a genetic condition, and that means it can be passed from parents to children. A coloboma can also be part of a genetic syndrome that causes other changes, in addition to faults in eye structures.

Children who develop these issues do so early in life, as researchers say that the fissure in developing babies should close between weeks five and seven of pregnancy. Once they emerge, they remain even as the baby grows bigger during the rest of the pregnancy.

These issues are relatively rare, and the Royal National Institute of Blind People says about 1 in 10,000 births involve a coloboma. But when they develop, they can be serious. Gaps in eye structure can lead to eye illnesses that cause pain, disability, or both.

Coloboma Can Lead to Eye Disease

A coloboma on or inside the eyeball represents a weak spot. That vulnerability can lead to changes in pressure or alterations in normal function. Sometimes, those changes lead to the development of other eye health issues.

The Royal National Institute of Blind People says coloboma increases your risk of:

  • Retinal detachment. If the coloboma is located on the retina or the optic disc, it can worsen and weaken the integrity of the eye. In time, delicate tissues at the back of the eye can loosen or pull away. Doctors can use surgery to prevent further damage, but the vision you lose during an episode may be permanent.
  • Glaucoma. A coloboma can change the way your eye drains, and that can lead to pressure buildup within the eye. Your optic nerve is sensitive to pressure, and if it rises too high, you could lose eyesight. Your doctor can use drops, surgery, or both to keep this issue in check.
  • Cataract. A cloudy lens is common for older people, but a coloboma can cause a cataract to form at an earlier age. A surgeon can replace your lens, but the procedure is delicate in those with coloboma.
  • New blood vessels. If the coloboma sits at the back of your eye, you could develop new capillary vessels. They're weak, and they're likely to break. When they do, blood can leak into the back of your eye, causing vision loss.

These are scary-sounding conditions. Thankfully, your doctor can help you prevent them.

During a routine eye exam, your doctor dilates your eye and examines both the front and the back. If your doctor spots a problem, you can come up with a treatment plan together.

If you have a coloboma, you may need exams more frequently than someone without one. Your doctor can put together a schedule that's right for you.

Life With a Coloboma

family of three looking over at horizon

In some cases, your coloboma will be visible when you peer into the mirror. Sometimes, the problem will be deeper in the eye, so no one will notice anything unusual about your eyes. Either way, you could have vision difficulties due to your unique structure, and you might need to make a few lifestyle adjustments.

The placement of your coloboma might impair your ability to focus your eyes. The significance of the impairment varies, depending on the size of the gap. If yours is small, you might need glasses while you read. If it's large, you might need large-print books.

The impact of your coloboma could also vary depending on the part of your eye you're using. You might see things right in front of you, for example, but struggle to see things off to the side. Your eye doctor can help you learn strategies to cope with this issue.

Coloboma of the iris can also impact your ability to handle bright light. Your eye can't fully constrict, and that can make standing outside on a sunny day very uncomfortable. Sunglasses, hats, or both could help you to block out the sun.

There is no cure for a coloboma, but that doesn't mean you can't live a long and happy life with the condition. With help from your doctor and a few key adjustments, you can move past the gap.

References

Facts About Uveal Coloboma. (June 2012). National Eye Institute.

Who Is At Risk for a Coloboma? (April 2018). American Academy of Ophthalmology.

Incidence, Ocular Findings, and Systemic Associations of Ocular Coloboma: A Population-Based Study. (January 2011). JAMA.

Coloboma. Royal National Institute of Blind People.

Coloboma Factsheet. (October 2018). Royal National Institute of Blind People.

Coloboma. FamilyConnect.

Coloboma. American Foundation for the Blind.