Cortical vision impairment is caused by a variety of neurological insults affecting the posterior visual pathways and /or visual cortex. Children with cortical vision impairment often have additional disabilities and ophthalmic findings, which can complicate the diagnosis of CVI. Children with multiple disabilities and a suspected vision impairment require a thorough investigation to determine the source of their reduced visual responses. Orthoptists may be involved in this process. The importance of distinguishing between reduced visual responses due to cortical vision impairment as opposed to attention difficulties or cognitive delay is discussed in this paper.