Cataract type and pupillary response to blue and white light stimuli

Abstract

We evaluated the pupil reaction to blue and white light stimulation in 70 eyes with cataract and in 38 eyes with a selective blue-light filtering intra-ocular lens. The diameter of the pupil before stimulation was set as baseline (BPD) and, after a stimulus duration of 1 s, the post-illumination pupillary response (PIPR) was measured using an electronic pupillometer. The BPD showed no significant difference among three grades of nuclear sclerosis (NS). In contrast, the PIPRs differed significantly among the NS grades eyes including with and without subcapsular cataract (SC) and IOL eyes for white light (p < 0.05, Kruskal-Wallis test), but not for blue light. Subcapsular opacity did not affect the BPD or PIPR in all cataract grades for either light stimulus. The tendency of larger PIPR in the pseudophakic eyes than the cataract eyes for both lights, however significant difference was found only for white light (p < 0.05 for white light, p > 0.05 for blue light). Our study demonstrates retention of the PIPR for blue light, but not for white light in cataract eyes. We also confirmed that the pupillary response in pseudohakic eyes with a selective blue light-filtering intra ocular lens was greater than that in cataractous eyes for white light.

Figure 1

Representative pupillometry responses for the three grades of nuclear sclerosis (NS) after chromatic stimulus with white light (a), and blue light (b). Black bars represent stimulus duration. The vertical scale is expressed as % constriction from the baseline pupil diameter (BPD). (a) The responses obtained with white light show the initial transient constrictions followed by short-duration sustained constrictions. The more severe the grade of NS, the smaller the amplitude of pupil constriction observed. (b) For blue light, after the initial transient constrictions, the following sustained constrictions were stronger than those for white light. Smaller amplitudes of pupil constriction were observed in the more severe NS grades, as with white light.

Figure 2

Results of baseline pupil diameter (BPD), the post-illumination pupillary response (PIPR), expressed as % constriction from BPD, obtained from eyes with various grades of nuclear sclerosis (NS) including with and without subcapsular sclerosis (SC) and IOL groups. (a) The BPR was not significantly different among the NS grades including with and without SC and IOL group (Kruskal–Wallis test, p > 0.05). (b) The PIPR for white light in the three grades of NS including with and without SC did not differ among the NS grades, but NS3 differed from IOL group (p = 0.037, Steel–Dwass test). (c) PIPR for blue light in the three grades of NS including with and without SC and IOL group. The PIPR for blue light was not significantly different among those groups (p > 0.05).

Figure 3

Parameters assessed for pupillary light response. The illustration shows the peak and sustained responses to light stimulation expected in healthy subjects. The vertical arrow indicates the stimulus onset. The duration is set as 1 s. The post-illumination pupillary response (PIPR) was determined as the value of constriction at 6 s after the light onset from baseline pupil diameter, and expressed as the % constriction from the baseline pupil diameter.

Figure 4

Spectral transmittance of the intra-ocular lens used in this study (solid line) and a 50-year-old human lens (dotted line), modified from the literature^,. This intra-ocular lens (ZCB00V; Abbott Medical Optics Inc., Santa Ana, CA) was newly introduced to minimize retinal toxicity and adverse effects on circadian rhythms by filtering 100% of short-wavelength light under 420 nm and allowing longer-wavelength light, including 460 nm, to enter the implanted eye.