Coloboma

What is a coloboma?

A coloboma is a congenital defect in the structure of either the eyelid or the eye itself. Coloboma can be inherited or can occur spontaneously.

What are the types of coloboma?

Coloboma can involve the eyelid, iris, choroid (a similar layer of eye tissue to the iris – lies between the retina and sclera in the posterior portion of the eye) and optic nerve.

What are the ocular associations of coloboma?

Microphthalmos, cataract, retinal detachment and poor vision if the coloboma involves the macular and optic nerve.

What are systemic associations of coloboma?

Coloboma may affect the eye structure in isolation or it can occur due to chromosomal abnormalities that involve other body structures. Coloboma can occur in conjunction with heart defects, choanal atresia, nervous system abnormalities, genital/urinary tract anomalies or ear malformations (as in CHARGE Syndrome).

Eyelid coloboma can be associated with Goldenhar Syndrome, which is characterized by a growth on the eye (limbal dermoid), abnormal eye movement (Duane Syndrome), ear abnormalities or vertebral abnormalities. Another syndrome that may be associated with coloboma of the lower lid is Treacher Collins Syndrome, which is characterized by depressed cheeks, a slanted appearance of eye and a small mandible.

What are the treatments for coloboma?

Lid coloboma can be repaired surgically if it causes dry eyes due to corneal exposure or are of a cosmetic concern. Many children with lid coloboma need tear substitutes to lubricate the cornea. Small aperture contact lenses or sunglasses can be useful to minimize the light exposure and may improve vision in some children.

Educational Implications

Behaviours or conditions that might indicate coloboma

• Decreased acuity.
• White pupil caused by an absent pupillary reflex.
• Poor red reflex.
• Photophobia
• Nystagmus
• Reduced depth perception.
• Cataracts
• Blurred vision (when both eyes affected).

What to do

• The young person should visit an ophthalmologist to determine diagnosis and treatment.
• Use high contrast materials.
• Maintain average to bright light conditions.
• Reduce glare.
• High contrast line markers and templates may be helpful for reading, finding maths problems, or locating other information.
• Reduce visual clutter.
• Visual aids for magnification may be required.
• Regular monitoring for retinal detachment.