Relative effectiveness of a blue light-filtering intraocular lens for photoentrainment of the circadian rhythm.

PURPOSE

To compare the relative effectiveness of photoentrainment of the circadian rhythm by a blue light-filtering tinted intraocular lens (IOL) (AcrySof Natural SN60), an untinted UV-only filtering IOL (AcrySof SA60), and human lenses in 4 age groups.

SETTING

Scientific consultant and Department of Biological Structure and National Primate Research Center, University of Washington, Seattle, Washington, USA.

METHODS

Three of 8 action spectra for circadian photoentrainment published from 2001 to 2007 were used to compute the relative effectiveness of the cumulative photon flux absorption from 400 to 600 nm reaching the retina from 4 light sources through the cornea, pupil, and 6 lenses.

RESULTS

The effectiveness of the tinted IOL was 35% to 54% and 69% to 114% greater with the action spectra of 2002 to 2007, with a peak around 484 nm and 492 nm, respectively, compared with the 2001 action spectra, with a peak around 460 nm. The difference in effectiveness between the 2 IOLs ranged from 32% to 12%. With newer action spectra, differences in effectiveness between the tinted IOL and the lenses of a young standard observer and a 30- to 39-year-old were age dependent (+7% to -10% and +6% to -13%, respectively).

CONCLUSIONS

The tinted IOL was significantly more effective for photoentrainment of the circadian rhythm with newer action spectra. The computational results suggest that the effectiveness of the tinted IOL in 60- to 85-year-old patients would be within +6% to -13% of that in 30 to 39 year olds. Both tinted and untinted IOLs are expected to be effective for melatonin suppression under average household illumination.