Ocular Coloboma
Ocular Coloboma
Coloboma is a congenital malformation resulting from incomplete closure of the embryonic fissure during fetal development. Incidence is approximately 1 in 10,000 births.
Key Points
- Can affect multiple parts of the eye
- Often bilateral (60% cases)
- May be isolated or syndromic
- Significant cause of pediatric visual impairment
- Requires genetic counseling
Embryological Basis
Development Timeline
- Week 4: Optic vesicle formation
- Week 5: Optic cup formation
- Week 7: Embryonic fissure closure
- Disruption Period: 5-7 weeks gestation
Classification by Location
- Lid Coloboma:
- Upper or lower lid defects
- May cause exposure keratopathy
- Iris Coloboma:
- Keyhole appearance
- Usually inferior location
- Can cause photophobia
- Lens Coloboma:
- Notching of lens equator
- May affect zonular support
- Choroidal Coloboma:
- White excavated defect
- High risk of retinal detachment
- Retinal Coloboma:
- Often accompanies choroidal defect
- Can affect central vision
- Optic Disc Coloboma:
- Enlarged excavated disc
- May involve macula
Clinical Manifestations
Visual Symptoms
- Vision Impact:
- Variable visual acuity
- Visual field defects
- Photophobia
- Glare sensitivity
- Associated Findings:
- Microphthalmia
- Nystagmus
- Strabismus
- Refractive errors
Specific Features by Location
- Iris Coloboma:
- Typical inferior keyhole
- Light sensitivity
- Cosmetic concerns
- Chorioretinal Coloboma:
- White excavated defect
- Variable size and shape
- May involve macula
- Optic Nerve Coloboma:
- Morning glory appearance
- Central scotoma
- Serous detachment risk
Diagnostic Approach
Initial Assessment
- History:
- Family history
- Gestational history
- Developmental milestones
- Associated symptoms
- Physical Examination:
- Complete eye examination
- Facial dysmorphism
- Systemic features
Ocular Examination
- Visual Assessment:
- Age-appropriate testing
- Visual field testing
- Color vision
- Anterior Segment:
- Slit lamp examination
- Gonioscopy when needed
- Anterior chamber depth
- Posterior Segment:
- Dilated fundoscopy
- Indirect ophthalmoscopy
- RetCam imaging
Imaging Studies
- B-scan ultrasonography
- OCT imaging
- MRI orbit/brain
- Genetic testing
Treatment Approaches
Visual Rehabilitation
- Refractive Correction:
- Spectacles
- Contact lenses
- Specialized contact lenses for iris defects
- Amblyopia Management:
- Patching therapy
- Visual stimulation
- Low Vision Aids:
- Magnifying devices
- Electronic aids
- Educational support
Surgical Interventions
- Eyelid Surgery:
- Lid reconstruction
- Corneal protection
- Iris Prosthesis:
- Custom iris implants
- Cosmetic contact lenses
- Retinal Surgery:
- Detachment repair
- Prophylactic laser
Associated Syndromes and Genetics
Major Associated Syndromes
- CHARGE Syndrome:
- Coloboma
- Heart defects
- Atresia choanae
- Retardation of growth
- Genital abnormalities
- Ear anomalies
- CHD7 gene mutations
- Retinochoroidal Coloboma Syndrome:
- PAX6 gene mutations
- Variable expressivity
- Cat Eye Syndrome:
- Iris coloboma
- Anal atresia
- Preauricular tags
- Chromosome 22 abnormality
Other Associated Conditions
- Genetic Associations:
- PAX2 mutations
- SOX2 mutations
- OTX2 mutations
- SHH pathway genes
- Systemic Conditions:
- Goldenhar syndrome
- Treacher Collins syndrome
- Aicardi syndrome
- Kabuki syndrome
