Effect of blue-blocking lenses on colour discrimination.

Clinical Relevance: Tinted lenses may adversely affect colour discrimination. Before recommending tinted lenses to patients, practitioners should bear in mind any effects on colour discrimination. The effects of 'blue-blocking' spectacle lenses with high luminous transmittance on colour vision is not a concern.

Background: Blue-blocking lenses have been widely promoted by manufacturers and practitioners. The more blue-blocking lenses are known to affect colour vision significantly but there has been no study of the effects of 'blue-blocking' spectacle lenses.

Methods: The transmittances of commercially available lenses were measured and the three lenses with the lowest blue light transmittance were selected. Subjects undertook the following computer-based colour vision tests: Colour Assessment and Diagnosis; the Cambridge Colour Test; and the Farnsworth-Munsell 100 Hue Test.

Results: Blue and luminous transmittances of lenses were documented. The reduction in blue transmittance varied from 12 to 40 per cent (two to 30 per cent compared with an untinted lens). The lenses were found to have no significant, statistical or possibly practical, effect on the results of the three colour vision tests (t-test, analysis of variance, Mann-Whitney, Kruskal-Wallis).

Conclusion: The modest blue light transmittance reduction of the 'blue-blocking' spectacle lenses examined was not sufficient to have a statistically significant effect on colour vision.