Visual stress is a controversial topic within optometry, particularly regarding its management and whether specific qualifications should underpin the use of coloured overlays.

Visual stress describes visual–perceptual symptoms triggered by text or high-contrast patterns, rather than a refractive or ocular pathology. Its neurophysiological basis is not fully understood. Symptoms may include visual discomfort, distortion of text, headaches and reading fatigue (Wilkins, 2002; 1995).

Previously termed Meares–Irlen syndrome, Irlen syndrome or scotopic sensitivity syndrome, the condition is now more commonly referred to as visual stress, reflecting a shift away from implying a specific causal mechanism (SASC, 2025; Irlen, 1991; Meares, 1980).

Coloured overlays and precision tints may provide symptom relief for some people, but evidence for their routine clinical use remains mixed (Howard-Jones, 2014; Stein, 2014; Wilkins, 2002). Any intervention should be approached cautiously, with clear communication about the limits of current evidence and appropriate professional training (Suttle and Conway, 2025).