Visual acuity in children with coloboma - Clinical features and a new phenotypic classification system

Objective: The aims of this study were to describe the clinical features an d biometric findings in the eyes of children with coloboma and to develop a classification of coloboma that correlates with visual function. Design: Retrospective observational case series. Participants: One hundred thirteen children and young adults (48 female, 65 male) aged 0 to 20 years with 196 eyes having coloboma. Methods: Children with coloboma were recruited from schools for the blind, integrated education programs, schools for the mentally handicapped, commun ity-based rehabilitation services, and hospital clinics in Andhra Pradesh, India, between January 1998 and January 1999. Visual function was assessed, including distance and near visual acuity (VA), and navigational vision. T he corneal diameter and axial length of eyes were measured wherever possibl e. Main Outcome Measures: Anatomic site of coloboma, association with microcor nea and/or microphthalmos, VA, presence of navigational vision and reading vision. Results: Of 196 eyes with colobomatous malformations, 11 had microphthalmos with cyst, and 185 eyes had coloboma (associated with microcornea in 155 e yes and with a normal corneal diameter in 30). Microphthalmos was present i n 72 of the 185 eyes with coloboma, of which 71 of 72 also had microcornea. The prognosis for vision depended on the phenotype of the better eye. Micr ophthalmos with cyst had the worst prognosis (VA < 3/60, 100%; reading and navigational vision, 0%). Microcornea with microphthalmos had a worse progn osis than microcornea without microphthalmos (VA < 3/60. 66.7% vs. 23.3%; u nable to read N10: 66.7% vs. 34.1%; no navigational vision: 30.6% vs. 6.73% ). Simple coloboma (no microcornea or microphthalmos) had the best prognosi s (VA < 3/60: 6.7%; able to read N10: 93.3%; navigational vision: 100%), A corneal diameter <6 mm had a poor visual prognosis, whereas a corneal diame ter >10 mm had a good prognosis. Conclusions: A phenotypic classification o f coloboma is proposed, which in this study showed a good correlation with visual acuity, reading, and navigational vision. Microphthalmos with cyst h ad the worst prognosis, coloboma with microcornea and microphthalmos a poor prognosis, coloboma with only microcornea had an intermediate prognosis, a nd simple coloboma had the best prognosis. (C) 2000 by the American Academy of Ophthalmology.