Blue-Light Filtering Increases the Brightness of Natural Images in Pseudophakic Adults

Several studies have suggested that blue-light filtering (BLF) can enhance the perception of brightness. Evidence for this effect, however, in pseudophakic patients, particularly using natural images, is lacking. The present study tested whether a common BLF spectral profile, often used in intraocular lens (IOL) designs, would influence brightness perception of natural images in pseudophakic individuals.

Forty pseudophakic participants (M = 71.15 ± 2.27 years) with 20/40 or better best-corrected visual acuity implanted with clear IOL implants completed a brightness matching task. Participants viewed a series of natural images through both a clear extraocular filter and a BLF test lens. The test lens was designed to approximate a typical BLF IOL transmission profile. Filter conditions were counterbalanced and randomized. Participants adjusted a short-wave deficient comparison field until the natural scene and the comparison fields were perceived as equally bright. Matched luminance values (log relative energy, LRE) were recorded across six trials per image. Images were achromatic or short-, mid-, and long-wave dominant.

Averaged across all images, the clear lens ( $\overline{X}$  = 2.74 ± 0.14) resulted in significantly lower (t _[78] = -2.529, p = 0.007) LRE values compared to the BLF test lens ( $\overline{X}$  = 2.82 ± 0.15) indicating a modest (∼17%) increase in perceived brightness with the BLF lens. This effect was observed for four of five natural images tested and was not dependent on image contrast or chromatic content.

The BLF produced a significant and consistent increase in perceived brightness in pseudophakic adults. These findings provide direct psychophysical evidence that clinically relevant BLF profiles can influence brightness under natural viewing conditions. Information of this type is necessary for the evaluation of BLF IOL designs and their effects on functional visual experiences following cataract surgery.