Handheld chromatic pupillometry detects preclinical retinal dysfunction in patients with diabetes mellitus

Abstract

Purpose : To evaluate the ability of handheld chromatic pupillometry to reveal retinal neural dysfunction in diabetic patients with and without diabetic retinopathy (DR).

Methods : In this cross-sectional study we included 82 patients with type 2 diabetes mellitus (DM) and 94 age-matched controls (60.4 ± 8.4 years, 43.6% males). The DM population included patients without (n = 25, 64.7 ± 6.3 years, 44.0% males) and with DR (n = 57, 60.3 ± 8.5 years, 64.9% males). At inclusion, all patients with DR were ocular treatment-naïve. Changes in pupil diameter in response to 10-second ramping-up (12.5 - 14.5 log photons/cm²/s) blue (469 nm) and red (640 nm) light stimuli were assessed monocularly, in clinics, using a custom-built handheld pupillometer. Baseline-adjusted constriction amplitudes and post-illumination pupillary responses (PIPR), were compared between controls, DM without DR, and DR. Net PIPR was defined as the difference between blue and red PIPR. The relationship between pupillary responses and glycemic control (glycated hemoglobin A1c [HbA1c] levels) was also explored in diabetics.

Results : Maximal constriction amplitudes to both blue and red lights were decreased in DR compared to DM without DR (P = 0.02; P = 0.02), and in DM without DR compared to controls (P = 0.001; P = 0.006). Net PIPR was decreased in both DR and DM without DR compared to controls (P = 0.03; P = 0.02), suggesting a wavelength-dependent (and hence afferent) pupillometric dysfunction in diabetics with or without DR. Patients with poor glycemic control (HbA1c ≥ 8.0%; n = 19) showed reduced maximal constriction amplitudes to both blue (P = 0.02) and red (P = 0.01) lights compared to patients with better control (HbA1c < 8.0%; n = 38). The distribution of patients with and without DR was not significantly different between the two groups.

Conclusions : Handheld chromatic pupillometry can detect a loss of retinal neural function in diabetic patients, even in the absence of DR. Pupillometric responses show greater reduction in patients with poor glycemic control. Longitudinal studies will establish the possible prognostic value of early retinal dysfunction in diabetes.

This is a 2020 ARVO Annual Meeting abstract.

 

Figure 1. Maximal pupillary constriction amplitudes to blue (A) and red (B) lights, and net PIPR (C) in controls, DM without DR, and DR. Difference between groups is indicated as * for P < 0.05, ** for P < 0.01, and *** for P < 0.001.