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
