Sight issues, which can be eye-related or brain-related, are common among people with learning disabilities. Premature birth or subsequent developmental delays can cause damage to the areas of the brain that process vision, leading to cortical visual impairment. Eye-related and brain-related sight issues can manifest as impaired visual perception causing, for example, difficulties with light perception, colour perception, object perception or movement perception. People with learning disabilities may display behaviours indicative of visual perception issues, but such behaviours are often ignored or misinterpreted. This article explains the causes and consequences of cortical visual impairment, describes visual perception issues that commonly arise from ocular/retinal or cortical causes, and outlines how learning disability nurses can detect the presence of visual perception issues in service users.