Is there a benefit of prescribing coloured lenses for adults with symptoms of visual stress?

Abstract

Introduction
Visual stress (VS) is a reading disorder characterised by visuoperceptual distortions and aversion to striped lines of text (‘pattern glare’). Precisely tinted spectacle lenses may reduce perceptual discomfort, by attenuating aversive visual information reaching a hyperexcitable visual cortex. Uncertainty remains regarding precision tint efficacy, owing to a limited evidence base.

Aims
This thesis aimed to investigate whether there is a significant and clinically meaningful benefit to prescribing coloured lenses for adult readers with symptoms of VS.

Methods
A double-masked placebo-controlled crossover trial formed the principal investigation of this thesis. Of 1378 undergraduates screened, 213 were identified with characteristics of VS and invited to participate. 57 recruited participants wore coloured spectacles with experimental and control tints (determined by Intuitive Colorimetry™), each for 6-weeks followed by a 2-week wash-out. Control lens colour fell outside the area of beneficial effect for optimally-tinted experimental lenses but was non-aversive. Wilkins Rate of Reading Test (WRRT) reading speed and mid-spatial frequency pattern glare sensitivity (PGT), were measured with both interventions. Secondary outcome measures included reading symptoms and additional indices of reading performance. Participants identified the most beneficial at trial endpoint, in a blinded head-to-head comparison. Effect of chromatic separation between tints was also explored.

Results
There was a significant increase in reading speed (p=0.026, ηp2=0.031) and decrease in pattern glare (p<0.001, ηp2=0.256) with both lenses. However, there was no significant difference between interventions (WRRT: p=0.678, ηp2=0.002; PGT: p=0.81, np2=0.009). Comparable changes in reading symptoms and secondary reading test rates manifested with both interventions. ~60% of participants chose experimental spectacles during the head-to-head. Yet, this did not differ significantly from chance (p=0.185). Chromatic separation was not significantly associated with between-lens WRRT performance (p=0.277, ρ=-0.146).

Conclusion
There is a modest benefit of prescribing coloured lenses for adults with VS, but the role of chromatic precision in the provision of coloured filters may not be as critical as previously thought. However, when realistic clinical expectations and individual variability in response to colour are considered, the use of coloured lenses may represent a useful intervention for adults with symptoms of VS.

Date of Award	Jun 2026
Original language	English
Sponsors	Department for the Economy
Supervisor	Sara McCullough (Supervisor) & Julie-Anne Little (Supervisor)