Coloboma
👁️ Coloboma
Coloboma is a congenital defect caused by incomplete closure of the embryonic optic fissure. It may affect the iris, retina, choroid, optic disc or eyelid. Severity varies from an isolated keyhole-shaped pupil to significant visual impairment if the posterior segment or optic nerve is involved.
🔍 Clinical Features
- Keyhole or irregular pupil if iris coloboma
- Reduced visual acuity if macula or optic nerve involved
- Visual field defect
- Photophobia or glare
- Strabismus or nystagmus in more severe cases
- May be unilateral or bilateral
⚠️ Associations
- Microphthalmia
- Cataract
- Retinal detachment
- CHARGE syndrome
- Other craniofacial, cardiac, renal or neurological anomalies
- Family history of congenital eye abnormality
🧪 Assessment
- Check visual acuity and red reflex
- Examine pupil shape and ocular alignment
- Refer to ophthalmology for dilated fundal examination
- Consider genetics or paediatric assessment if bilateral, syndromic features or systemic abnormalities
✅ Management
- No treatment is needed for a small isolated iris coloboma if vision is normal
- Tinted lenses or cosmetic contact lenses may help glare or appearance
- Correct refractive error and treat amblyopia early in children
- Monitor for retinal complications, especially retinal detachment
- Provide genetic counselling where inherited or syndromic disease is suspected
The important clinical point is to distinguish a cosmetic anterior coloboma from posterior segment involvement. Iris coloboma may have little functional impact, whereas chorioretinal or optic nerve coloboma can affect acuity, fields and retinal stability.
📞 Refer
- Any suspected new diagnosis of coloboma
- Reduced vision, abnormal red reflex, strabismus or nystagmus
- Bilateral disease or suspected syndromic features
- Symptoms of retinal detachment such as flashes, floaters or curtain-like visual loss
