ADHD is a neurological disorder categorized by symptoms of inattention - difficulty sustaining attention and mental effort, forgetfulness, and distractibility; hyperactivity - fidgeting, excessive talking, and restlessness; and impulsivity - difficulty waiting for one’s turn and frequent interruption of others. 
While the cause of ADHD is unknown, it has been suggested that dysfunctional cortical activation and variations in stimulus processing may play an important role in behavioural inhibition, self-regulation and stimulus control. 
Visual stress is a visual-perception disorder that leads to increased cortical activation and difficulty processing visual stimuli such as flicker (from fluorescent lights), glare, contrast and patterns (found in text and lined paper). The resulting symptoms reported including inattention - difficulty concentrating and being easily distracted when reading, writing or when under fluorescent lighting (most classrooms); hypersensitivity to certain visual images, and fidgeting.
A 2013 study in Australia notes that previous investigations of Meares-Irlen Syndrome/SSS (aka visual stress) have identified several clinical features of symptom manifestation which are strikingly similar to those found in ADHD. Their study identified a strong degree of symptom overlap and stated, “it is likely that many individuals with SSS may be misdiagnosed with ADHD.” 
A 2004 study in Germany found that typical features of handwriting improve with coloured writing paper and lead to better overall legibility of the work. 
Practical implications of these findings are to provide individuals with ADHD with additional, non-intrusive assistive tools to support the regulation of attention. The tools that work to address visual stress symptoms include coloured paper, reading overlays, screen tinting software, and precision tinted lenses and should be investigated as a potential solution for individuals presenting with ADHD symptoms.