Patients with a functional neurological disorder (FND) experience a lower psychological quality of life and have more mental health concerns. These patients deserve to be treated with a treatment that is evidence-based and proven effective. However, when we look children or adolescents with functional visual disorder (FVD; a subgroup of FND), we see that there is not much evidence for the effectiveness of their treatments. Possible reasons for this lack of evidence and the difficulties in studying children and adolescents with FVD are discussed in this article. This article concludes with possible ways of persuading children and adolescents with FVD in participating in research.