Awareness of a rare eye condition has recently surfaced thanks to Olympic gymnast Stephen Nedoroscik, who helped Team USA win the bronze medal after his pommel horse routine during the Paris 2024 Summer Games. Nedoroscik revealed he has two eye conditions that severely impact his vision—coloboma and strabismus.
Understanding Coloboma
Coloboma affects about 1 out of every 10,000 babies each year. It occurs when the eye does not fully develop into a complete sphere during gestation. This leads to a gap, or missing area, in the structure of the eye. Typically, this gap is located in the lower part of the eye and can affect various parts of the eye including the iris, retina, lens, or optic nerve.
Cases of coloboma that affect both eyes are believed to be genetic. More commonly, however, the condition occurs by chance, according to the American Academy of Ophthalmology.
“The degree of vision loss depends on the extent of the coloboma and can range from completely normal vision to legal blindness,” says Marielle Young, MD, chief of pediatric ophthalmology at the John A. Moran Eye Center. “Even those who experience significant vision loss in one eye due to coloboma can lead normal lives.”
Recognizing Coloboma
Coloboma is present at birth. The condition can cause an abnormal pupil shape—often described as a "cat-eye" appearance—because the iris did not develop normally. Severe cases can lead to reduced vision in one or both eyes. Other times, the only symptom may be light sensitivity.
How Coloboma Affects Vision
The impact of coloboma on vision varies greatly from one individual to another, depending on how much of the eye structure is missing. Coloboma can cause vision problems including:
- Light sensitivity: In cases where only the iris is affected, the primary symptom is an irregularly shaped pupil that does not fully constrict in response to light.
- Low or reduced vision: When a large amount of the retina and choroid is involved, individuals can have reduced visual acuity or constricted visual fields.
- Vision loss or blindness: If the condition involves the central retina or optic nerve, it can lead to significant vision loss or even blindness in the affected eye or eyes. This happens because the retina, which is essential for capturing light and sending visual signals to the brain, is incomplete or nonfunctional.
Treatment and Management
Currently, there is no cure for coloboma, and treatment focuses on managing symptoms and maximizing vision.
- Glasses or contacts: Eyeglasses or contact lenses can help people with coloboma see more clearly. Specialized contact lenses or tinted glasses can help those with light sensitivity.
- Low vision aids: If vision loss can’t be corrected with glasses or contacts, special devices like bioptic telescopes may be used to improve vision.
- Surgery: If coloboma impacts the iris, doctors can do a surgery to treat light sensitivity.
“If coloboma causes significant visual impairment in one or both eyes, glasses are recommended to prevent injury and protect the better-seeing eye,” Young says.
Living with Coloboma
Most individuals with coloboma experience minimal visual impairment and can function normally in daily life.
“People with mild coloboma can often lead normal lives with few adjustments,” Young says. “For individuals with bilateral coloboma, affecting both eyes, the impact on daily life can be more profound.”
Although there is no cure, supportive interventions and lifestyle adjustments can help manage symptoms and improve quality of life for people with coloboma. For those with significant vision loss, early intervention and protective measures are crucial to encourage normal visual development.