Efficacy of coloured lenses for patients diagnosed with visual stress

Colour overlays and lenses are used to relieve symptoms in some patients diagnosed with visual stress, but evidence to support this practice is lacking. In this small randomised crossover trial, a range of colours are beneficial and precise colour specification does not enhance this effect.

This randomised, double-masked crossover trial aimed to test effectiveness of precisely selected lens tints for visual stress.

Twenty-nine participants aged 11 to 72 (mean 30) years diagnosed with visual stress were issued with their selected coloured overlay then with tinted lenses at two colour settings. An eye examination and coloured overlay test were followed by intuitive colorimetry to select a colour to minimise symptoms (optimal tint) and the closest setting at which the symptoms returned (sub-optimal, or placebo tint). The tints were worn for one month each in randomised order. Reading speed was measured using the Wilkins Rate of Reading Test, a subjective scale was used to gauge symptoms, and the patient was asked to indicate whether one of the tints alleviated their symptoms more than the other.

Reading speed was significantly higher with colour than without (p < 0.001), but was similar with the overlay and both tints (p = 1.0). Discomfort/distortion rating (1-7) was lower with colour than without (p < 0.001), but no difference was found between the overlay and both tints (p > 0.1). About half (47%) of the patients preferred/strongly preferred their optimal tint, and 39% preferred/strongly preferred their sub-optimal tint, while 14% had no preference.

While our patients read more quickly and were more comfortable when using a tint, there was no difference in outcome between the optimal and sub-optimal tints. These results suggest that for patients diagnosed with visual stress, precision tints are no more helpful than sub-optimal, placebo tints.