Microphthalmia/Anophthalmia/Coloboma Spectrum – RETIRED CHAPTER, FOR HISTORICAL REFERENCE ONLY

NOTE: THIS PUBLICATION HAS BEEN RETIRED. THIS ARCHIVAL VERSION IS FOR HISTORICAL REFERENCE ONLY, AND THE INFORMATION MAY BE OUT OF DATE.

Clinical characteristics: Microphthalmia, anophthalmia, and coloboma comprise the MAC spectrum of ocular malformations.

1. Microphthalmia refers to a globe with a total axial length that is at least two standard deviations below the mean for age.

2. Anophthalmia refers to complete absence of the globe in the presence of ocular adnexa (eyelids, conjunctiva, and lacrimal apparatus).

3. Coloboma refers to the ocular malformations that result from failure of closure of the optic fissure. Chorioretinal coloboma refers to coloboma of the retina and choroid. Iris coloboma causes the iris to appear keyhole-shaped.

Microphthalmia, anophthalmia, and coloboma may be unilateral or bilateral; when bilateral they may occur in any combination.

Diagnosis/testing: Molecular genetic testing (which can include sequence analysis, gene-targeted deletion/duplication analysis, and chromosome microarray analysis [CMA]) can identify a genetic cause in 80% of individuals with bilateral anophthalmia/severe microphthalmia and in up to 20% of all individuals with an ocular malformation in the MAC spectrum.

Genetic counseling: When an inherited or de novo chromosome abnormality or a specific syndrome is identified either by phenotypic findings or by genetic/genomic testing, genetic counseling is indicated based on the mode of inheritance for that condition.

Management: Treatment of MAC spectrum: Prosthetic intervention is appropriate for those with severe microphthalmia and anophthalmia. In many infants, an ocularist can start shortly after birth to expand the palpebral fissures, conjunctival cul-de-sac, and orbit using conformers of progressively increasing size. An oculoplastic surgeon can help determine the most suitable options for surgical intervention after age six months (when postnatal growth of the orbit can be assessed) and before the age that orbital dimensions are fixed (after which extensive orbital reconstruction may be required).

Children with reduced vision may benefit from visual aids and other visual resources as well as early intervention to help optimize psychomotor development, educational endeavors, life skills, and mobility. Protection of the healthy eye in those with unilateral involvement is recommended.