Irlen syndrome: systematic review and level of evidence analysis

Scotopic sensitivity syndrome, later called Meares-Irlen syndrome or simply Irlen syndrome (IS) has been described as symptoms of poor reading ability due to poor color matching and distorted graphic images. Individuals with this syndrome are considered slow, ineffective readers with low comprehension and visual fatigue. It is still uncertain whether the disease pathophysiology is an independent entity or part of the dyslexia spectrum. Nevertheless, treatments with lenses and colored filters have been proposed to alleviate the effect of the luminous contrast and improve patients' reading performance. However, no evidence of treatment effectiveness has been achieved.

The aim of the present study was to obtain evidence about IS etiology, diagnosis and intervention efficacy.

A systematic review was performed covering the available studies on IS, assessing the available data according to their level of evidence, focusing on diagnostic tools, proposed interventions and related outcomes.

The data showed high heterogeneity among studies, and lack of evidence on the existence of IS and treatment effectiveness.

The syndrome as described, as well as its treatments, require further strong evidence.