Retinal neural dysfunction in diabetes revealed with handheld chromatic pupillometry

Abstract

Background To evaluate the ability of handheld chromatic pupillometry to reveal and localise retinal neural dysfunction in diabetic patients with and without diabetic retinopathy (DR). Methods This cross‐sectional study included 82 diabetics (DM) and 93 controls (60.4 ± 8.4 years, 44.1% males). DM patients included those without (n = 25, 64.7 ± 6.3 years, 44.0% males) and with DR (n = 57, 60.3 ± 8.5 years, 64.9% males). Changes in horizontal pupil radius in response to blue (469 nm) and red (640 nm) light stimuli were assessed monocularly, in clinics, using a custom‐built handheld pupillometer. Pupillometric parameters (phasic constriction amplitudes [predominantly from the outer retina], maximal constriction amplitudes [from the inner and outer retina] and post‐illumination pupillary responses [PIPRs; predominantly from the inner retina]) were extracted from baseline‐adjusted pupillary light response traces and compared between controls, DM without DR, and DR. Net PIPR was defined as the difference between blue and red PIPRs. Results Phasic constriction amplitudes to blue and red lights were decreased in DR compared to controls (p < 0.001; p < 0.001). Maximal constriction amplitudes to blue and red lights were decreased in DR compared to DM without DR (p < 0.001; p = 0.02), and in DM without DR compared to controls (p < 0.001; p = 0.005). Net PIPR was decreased in both DR and DM without DR compared to controls (p = 0.02; p = 0.03), suggesting a wavelength‐dependent (and hence retinal) pupillometric dysfunction in diabetic patients with or without DR. Conclusions Handheld chromatic pupillometry can reveal retinal neural dysfunction in diabetes, even without DR. Patients with DM but no DR displayed primarily inner retinal dysfunction, while patients with DR showed both inner and outer retinal dysfunction.

Diabetic retinopathy: Looking forward to 2030

“…Histological studies on enucleated eyes also corroborate these findings, showing reductions in retinal ganglion cell density in eyes with DR ( 32 ). Functional assessments in diabetes reveal reductions in contrast sensitivity, visual field defects, electrophysiologic deficits, and impaired pupillary responses ( 33 – 38 ).…”

“…Functional assessments such as electrophysiology, visual field perimetry and pupillometry are often time-consuming and resource-intensive. Recently, a portable, handheld chromatic pupillometer was shown to able to provide rapid, clinic-based assessment of retinal neural function in diabetes ( 38 ). Such findings, however, need to be replicated and validated in larger cohorts.…”

Extracellular Vesicles and Diabetic Retinopathy: Nano-sized Vesicles With Mega-sized Hopes

“…As DR is a neurovascular complication of diabetes, non-vascular cells, including retinal neurons and glial cells, are also affected, showing many abnormalities or accelerated apoptosis. Retinal microglia and astrocytes are two main sources of ROS causing oxidative stress in chronic neurodegeneration [4,18,19]. Diabetic retinal neurodegeneration is shown as a significant thinning of the inner retinal layers, including the retinal nerve fiber layer, and ganglion cell layer [20][21][22].…”

Spotlighting retinal diseases

“…In a report of diabetic retinopathy during pregnancy that involved 172 women, Widyaputri et al 12 made the observation that one in nine had sight‐threatening disease, a rate that persisted during the post‐partum period. Tan et al 13 introduced parameters measured with a handheld chromatic pupillometer that indicated diabetic retinopathy, and also identified individuals with diabetes but without clinical retinopathy. Meyer et al 14 presented the results of a randomised clinical trial, comparing 3‐monthly treatments with the intravitreal dexamethasone implant versus monthly intravitreal bevacizumab injections in 58 eyes of Aboriginal adults.…”