What are the effects of metopic synostosis on visual function?

Metopic synostosis is a premature fusion of the metopic cranial suture. Small case studies into the effects on vision have suggested that there is a raised incidence of astigmatic refractive error with increased risk of failure to develop normal vision if reconstructive surgery is delayed beyond 7 months of age. The aim of this study was to look at a much larger group of patients to give more statistical significance on the incidence of significant refractive error and strabismus in cases of metopic synostosis and compare this with that known for the general population of children at a similar age. A secondary objective was to look at the age at surgery and the visual outcome. A retrospective analysis of case notes was carried out for 64 children with a confirmed diagnosis of metopic synostosis attending the Oxford Craniofacial Unit. Twenty children (31%) were found to have a visual problem, with 18 needing glasses to correct a refractive error and 10 having strabismus. The nature of refractive error was generally hypermetropia, in some cases combined with low astigmatism (1.5 diopters [D] or less). Only 1 child was recorded as having more than 1.5 D of astigmatism. The age at surgery did not seem to influence visual outcome. The incidence of significant refractive error requiring correction and strabismus across the metopic group (31%) was higher than that found in the general population of children at a similar age (5%-11%). This reinforces the importance of orthoptic/ophthalmic surveillance in metopic synostosis.