Coloboma is a rare condition that occurs when part of the eye doesn't fully develop before birth, leaving a noticeable gap or “missing piece” in its structure. Although it's uncommon, Coloboma can affect people in very different ways, from minor cosmetic changes to serious vision problems. Understanding this condition is the first step toward early diagnosis, better management, and greater awareness. You'll learn what Coloboma is, why it happens, and what living with it really means. In this blog, we will learn about the causes, treatment and symptoms related to coloboma. Let’s dig deeper for more information.
What is Coloboma?
Coloboma eye is an abnormality that occurs before birth. It happens when part of the tissue that makes up the eye is missing. It can affect a single eye or both eyes. The most common and recognisable coloboma typically affects the pupil and iris of a human eye. When diagnosed with coloboma, you need to address the concern as soon as possible.
What are the Causes of Coloboma?
According to experts, babies get exposed to colobomas in the uterus itself. Changed or abnormal genes affect a child’s eye development as well. Other external factors or unhealthy habits, like smoking and drinking, especially during pregnancy, can also lead to the condition.
The optic fissure of the babies comes together to form the eyes, which takes place two months before their birth. If the fissure fails to close completely, it automatically causes colobomas in the eyes.
Does Coloboma Affect Vision?

Coloboma that is affecting the iris results in a ‘keyhole pupil’, usually not leading to the loss of vision. On the other hand, colobomas involving the retina result in the loss of vision in some specific parts of the visual field. Large retinal colobomas or those affecting the optic nerve (optic nerve coloboma) might cause low vision which can’t be corrected with glasses or contact lenses.
What are the Types of Coloboma?
There are different types of coloboma. Each type has different effects on the eyes. Let’s check them out at a quick glance:
Eyelid Colobomas: If a piece of the lower or upper eyelid is missing, it is referred to as eyelid colobomas.
Chorioretinal Colobomas: If a part of the retina is missing, it’s called chorioretinal colobomas.
Macular Colobomas: When the macula doesn’t develop properly, it’s known as macular colobomas.
Lens Colobomas: It is a condition where a lens piece is missing from the eyes. The change in lens shape caused by a notch or dent can cause blurred vision if the lens of the eye is affected by coloboma.
Optic Nerve Colobomas: It occurs as a result of incomplete closure of the embryonic fissure during development, which causes a defect in the optic nerve.
Uveal Colobomas: The middle layer of your eye, the uvea, sometimes gets missing. The condition is called uveal colobomas.
What are the Symptoms of Coloboma?

Some of the symptoms of coloboma are:
Low vision
A cat-eye-shaped pupil or a keyhole
Blindness or partial vision loss
Sensitivity to light
Nystagmus
It can typically cause:
Reduced peripheral vision
Difficulty with depth perception
A larger-than-usual blind spot
How to Diagnose Coloboma?
Coloboma is diagnosed by the doctor during an eye test of the child. To get a clearer view of the eye’s structure, the doctor may use advanced imaging tools like Optical Coherence Tomography (OCT) or retinal scans. These tests help identify any unusual gaps or changes in the eye, especially in important areas like the retina or optic nerve.
Treatment and Prevention of Coloboma
There is no specific treatment for coloboma or the missing tissue in the child’s eye. But certain treatments might improve the vision. They are-
Wear corrective lenses (glasses or contact lenses)
Wear an eye patch to prevent a lazy eye or amblyopia
Low vision aids
Surgical Intervention
Some people with iris colobomas can have surgery to change the appearance of their affected eye.
Genetic colobomas cannot be prevented during the time of pregnancy. However, some precautions can be taken to avoid the occurrence of colobomas. Genetic conditions are linked to certain environmental factors, including:
Drinking alcohol
Smoking or the use of any tobacco products
Using recreational drugs
Poor dietary preferences
Wrapping It Up
If the coloboma is visible, the eye specialists will perform an eye test and diagnose the given concern. But if the coloboma isn’t visible at all, one needs to undergo a comprehensive dilated eye exam. With the right care, like vision correction, protective eyewear, or low vision support, many people with coloboma live full, active lives. If you or someone you know shows signs of this condition, don’t delay a visit to an eye care professional. The sooner it’s diagnosed, the better the chances of managing it effectively and confidently.
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