Difference in pupillary response to red and blue color stimuli between glaucoma and Leber hereditary optic neuropathy...

To compare pupillary responses during two-color light stimulation and the post-illumination pupillary response (PIPR) between patients with Leber hereditary optic neuropathy (LHON) and established optic atrophy and patients with primary open-angle glaucoma (POAG) who have central visual dysfunction with similar magnitude to that of the LHON patients.

Fourteen normal controls, eight patients with POAG and mean deviation of the Humphrey visual field and circumpapillary retinal nerve fiber layer and ganglion cell/inner plexiform layer thickness measured using optical coherence tomography being comparable to those of LHON patients, and nine patients with LHON were included. Using a handheld electronic pupillometer, pupil diameter of the eye contralateral to the stimulation was recorded during a 7 s baseline period, a 10 s red light stimulation followed by a 40-s post-stimulation period, and a 10 s blue light stimulation followed by a 40 s post-stimulation period.

The ratio of pupil diameter at 6 s after blue, but not red, light offset as well as the subtraction of difference between the baseline pupil diameter and the mean pupil diameter during the 30 s post-illumination using red stimulus from the counterpart using blue stimulus was significantly larger in POAG patients than in the other two groups. The maintenance of pupillary constriction during blue light stimulation was significantly reduced in POAG patients compared with the other two groups.

Compared with POAG patients who had comparable macular structural and functional damage, LHON patients showed better pupillary responses during blue light stimulation and PIPR, reflecting preserved ipRGC function.