Reduced Optic Nerve Head Blood Flow Correlates With an Impaired Postillumination Pupil Response in Glaucoma

In glaucomatous eyes, reduced optic nerve head blood flow was significantly associated with impaired intrinsically photosensitive retinal ganglion cell function, as assessed by the postillumination pupil response, independent of age and other confounding factors.

To investigate whether ocular nerve head (ONH) blood flow is associated with impaired intrinsically photosensitive retinal ganglion cell (ipRGC) function, assessed by the postillumination pupil response (PIPR), in eyes with glaucoma.

This cross-sectional study included 114 eyes from 114 patients with glaucoma (mean age, 69.5 y). PIPR was evaluated by measuring pupil diameters after red and blue light exposure. The main PIPR outcomes were the amplitudes of red and blue 6-second PIPR, which are pupil diameters 6 seconds after red and blue light exposure. ONH blood flow was assessed by the tissue-area mean blur rate (MBR) using laser speckle flowgraphy.

A significantly higher blue 6-second PIPR amplitude was observed in the low tissue-area MBR group than in the high tissue-area MBR group (93.5% vs. 91.1%, P =0.043). After adjusting for age, sex, body mass index, hypertension, diabetes, intraocular pressure, and axial length, a multivariable linear regression analysis showed that tissue-area MBR inversely correlated with the blue 6-second PIPR amplitude (regression coefficient=-0.40; 95% CI, -0.73 to -0.06; P =0.021), but not the red 6-second PIPR amplitude (regression coefficient=-0.01; 95% CI, -0.36 to -0.15; P =0.42).

Lower ONH blood flow in eyes with glaucoma correlated with impairments in ipRGCs independent of potential confounders, including age.