Visual function and performance with blue-light blocking filters in age-related macular degeneration

Some dispute has occurred over the use of blue-light-attenuating intraocular lenses in age-related macular degeneration (AMD), as they may reduce scotopic vision. This study aimed to determine if a blue blocking filter would affect performance during eye-hand coordination and mobility tasks in scotopic illumination, psychophysically measured scotopic sensitivity or colour discrimination in AMD patients.

Scotopic measures performed with and without a blue-attenuating filter included a mobility obstacle course, manipulation of cylindrical blocks and a psychophysical dark-adapted full-field flash test. A navy and blue sock colour sorting task evaluated photopic colour discrimination. Subjects were 22 bilateral pseudophakes with early AMD and visual acuity >6/24.

On average with the filter, there was a 13% increase in time during the block test. The differences in time and number of bumps with versus without the filter were not significant for the mobility course. Performance with and without the filter was well correlated for the blocks (r = 0.70), flash test (r = 0.83) and mobility (r = 0.66), and the regression slopes were not significantly different from unity. 77% of subjects misidentified at least one navy sock as black with the filter compared with 9% without, with a significant increase in such misidentifications with the filter.

The difference in scotopic visual function or performance with versus without a blue-blocking filter most likely does not produce a clinically significant effect or risk; however, detection of navy colour may be impaired.