C is for Coloboma.

A coloboma is a congenital defect in the structure of the eye or eyelid.


Answers to Frequently Asked Questions

What is coloboma?

Coloboma is used to describe conditions where normal tissue in or around the eye is missing from birth. Coloboma comes from a Greek word which means “curtailed”.

What is uveal coloboma?

Uveal coloboma can present as an iris coloboma (the iris is the colored part of the eye), with the traditional “keyhole” or “cat-eye” appearance to the iris, and/or as a chorio-retinal coloboma where the retina in the lower inside corner of the eye is missing.

How common is uveal coloboma?

Uveal coloboma is a rare condition that is not always well documented. Depending on the study and where the study was conducted, estimates range from 0.5 to 2.2 cases per 10,000 births. Some cases may go unnoticed because uveal coloboma does not always affect vision or the outside appearance of the eye.

Can uveal coloboma cause blindness?

Yes. Uveal coloboma is a significant cause of blindness. Studies estimate that 5 to 10 percent of blind European children have uveal coloboma or uveal coloboma-related malformations.

What are the different kinds of coloboma?

There are different kinds of coloboma, depending on which part of the eye is missing. These include:

  • Eyelid Colobma, in which a piece of the upper or lower eyelid is absent.
  • Lens Coloboma, in which a piece of the lens is absent. The lens will typically appear with a    notch.
  • Macular Coloboma, in which the center of the retina, called the macula, doesn’t develop  normally.
  • Optic Nerve Coloboma, which refers to one of two things:
    • Optic nerve coloboma in which an abnormal optic nerve is deeply “excavated” or hollowed out.
    • Optic nerve coloboma that is large enough to involve the optic nerve.

What causes uveal coloboma?

It is believed that uveal coloboma is primarily genetic in origin. “Genetic” means that the coloboma was caused by a gene that was not working properly when the eye was forming.

What are the symptoms of uveal coloboma?

There may or may not be any symptoms related to coloboma; it all depends on the amount and location of the missing tissue. People with a coloboma affecting the macula and the optic nerve will likely have reduced vision. In general, it is difficult to exactly predict what level of vision a baby will have only by looking at how much of the retina is missing.

People with a coloboma affecting any part of the retina will have what is called a “field defect”. A field defect means that a person is missing vision in a specific location. Because coloboma is located in the lower part of the retina, vision in the upper part of the field of vision will be missing. This may or may not be noticeable to the affected person.

A person with a coloboma affecting the front of the eye only will not have any decreased vision from it. Some people, however, have reported being more sensitive to light.

Can uveal coloboma be treated?

Patients with uveal coloboma should have yearly follow-up exams by an eye care professional. However, there is currently no medication or surgery that can cure or reverse coloboma and make the eye whole again. Treatment consists of helping patients adjust to vision problems through methods including:

  • Correcting any refractive error with glasses or contact lenses.
  • Maximizing the vision of the most affected eye in asymmetric cases. This may involve patching or using drops to temporarily blur vision in the stronger eye for a limited period of time.
  • Ensuring that amblyopia (lazy eye) does not develop in childhood in case of asymmetry. Sometimes amblyopia treatment (patching, glasses and/or drops) can improve vision in eyes even with severe colobomas.
  • Treating any other eye condition that may be present with coloboma, such as cataracts.

Nearly all of the above information is courtesy of the National Eye Institute, National Institutes of Health (NEI/NIH).

Can iScreen Vision detect coloboma?

It depends on the location and severity of the coloboma. There are many instances in which a colobma will create an irregular “red reflex” in the eye. A red reflex is when light is transmitted through the transparent portions of the eye and reflects off the retina, creating a reddish orange reflection in the eyes. Because iScreen Vision’s technology, called photoscreening, creates a digital red reflex image of the eye, a coloboma whose position or size interferes with a normal red reflex would normally be detected. When photoscreening is used to detect coloboma, you may hear it referred to as:  Coloboma Vision Screening, Coloboma Vision Testing, Pediatric Coloboma Vision Screening, or Pediatric Coloboma Vision Testing.

Pediatric Coloboma Vision Screening & Detection FAQs
These FAQs discuss topics including: Coloboma, Coloboma Vision Screening, Coloboma Vision Testing, Pediatric Coloboma Vision Screening, and Pediatric Coloboma Vision Testing.