---
title: What is iris coloboma?
description: "Iris coloboma is a congenital defect in which part of the iris tissue is missing, usually appearing as a keyhole-shaped gap extending downwards from the pupil. It results from incomplete closure of the embryonic fissure during eye development. ## Features…"
url: "https://bluefinvision.com/knowledge-base/topics/conditions-diseases/what-is-iris-coloboma/"
updated: "2025-12-11"
category: "Conditions & Diseases"
---

# What is iris coloboma?

Iris coloboma is a congenital defect in which part of the iris tissue is missing, usually appearing as a keyhole-shaped gap extending downwards from the pupil. It results from incomplete closure of the embryonic fissure during eye development.

## Features

The opening can vary in size from a small notch at the pupil margin to a large defect reaching towards the ciliary body. Coloboma may occur in isolation or be associated with coloboma of the lens, retina, or optic nerve.

- Typically involves the lower part of the iris
- Light may enter through the defect, causing glare or photophobia
- Visual acuity is often normal when only the iris is affected
- More extensive colobomas can significantly affect vision

## Management

Treatment focuses on reducing symptoms and protecting vision. Options include tinted lenses, cosmetic or occlusive contact lenses, and surgical iris reconstruction in selected cases.

- Comprehensive examination checks for associated posterior segment colobomas
- Genetic counselling may be considered, especially in syndromic cases
- Children require monitoring for amblyopia if vision is asymmetric
- Sun and glare protection can improve visual comfort