Complex sporadic colobomata

Classification of microphthalmos and coloboma

A new classification of microphthalmos and coloboma is proposed to bring order to the complexity of clinical and aetiological heterogeneity of these conditions. A phenotypic classification is presented which may help the clinician to give a systematic description of the anomalies. The phenotype does not predict the aetiology but a systematic description of ocular and systemic anomalies improves syndrome identification. There are two major classes, total and partial microphthalmos, and a subclassification which follows the embryology of the anomalies. The aetiological classification consists of three classes: (1) genetic (monogenic and chromosomal), (2) prenatally acquired (teratological agents and intrauterine deformations), and (3) associations. Genetic disorders give rise to malformations; prenatally acquired anomalies are disruptions or deformations. The aetiological classification can be applied to other congenital birth defects and improves counselling of families. Recurrence risks vary considerably between the classes.

Ocular choristomas

Choristomas are congenital lesions representing normal tissue(s) in an abnormal location. They are the most common epibulbar and orbital tumors in children. Epibulbar choristomas affect the cornea, limbus or subconjunctival space, and range in appearance from a small, flat lesion to a large mass filling most of the epibulbar region. Astigmatism is often present. Choristomas may be associated with coloboma, Goldenhar syndrome or epidermal nevus syndromes; those associated with the latter are often bilateral and extensive. Choristomas are occasionally familial. Surgery may be indicated to improve vision or cosmesis, or to impede growth. Although choristomas most commonly involve the epibulbar area, they can affect many areas of the eye and orbit, and often affect more than one area.