Nuijts MA, et al. - In children with a brain tumor, researchers ascertained if optical coherence tomography leads to earlier detection of visual impairment vs standard ophthalmological testing (VA, VF), as well as concentrated on the longitudinal connection between the course of visual function, course of disease and types of treatment. For this investigation, individuals (aged 0 to 18 years) with a newly diagnosed brain tumor are invited. The CCISS study, a prospective, observational, multicenter cohort study in The Netherlands, will increase awareness of visual impairment in children with different types of brain tumors. This research would show that optical coherence tomography contributes to earlier diagnosis of visual impairment in children with a brain tumor vs standard ophthalmological testing (ie, visual acuity, visual field testing). In addition, this study's systematic approach to ophthalmological follow-up will give us insight into the longitudinal relationship between the course of visual function, disease course, and types of treatment in brain tumor children.