Motion Diamond Stimulus (MDS): Utilizing contrast-generated illusory motion as a tool for measuring contrast sensitivity and visual function

Abstract

Purpose : Patients often report visual complaints not captured by standard visual acuity measures. This study aims to evaluate a novel digital tool known as MDS that utilizes contrast-generated illusory motion to measure visual function and contrast sensitivity (CS). The MDS provides data beyond traditional CS measures. The purpose of this study was to determine the practicality of using this tool in clinical practice and establish a control cohort without macular pathology and good visual acuity. The effect of pupil dilation on test performance was also assessed.

Methods : Recruitment for this IRB-approved study took place in the Northwestern Medicine ophthalmology clinic between Dec 2018 and Sept 2019. Exclusion criteria included macular pathology and visually significant cataracts. Study participants completed 3 assessments: the NEI-VFQ-25, Pelli-Robson CS Chart, and MDS. Monocular performance for the latter was recorded before and after dilation, for a total of 4 trials per patient. MDS output was graphed in an exponential fit for each participant. α and β values were compared using paired, two-tailed t-tests.

Results : The cohort comprised of 10 patients (20 eyes) with a mean age of 65 years. The majority of patients were following with retinal specialists after a resolving posterior vitreous detachment. The average LogMAR BCVA (±SD) was 0.058 (0.062). On MDS testing, at edge-width angle of 6 minutes, no differences were detected in contrast threshold levels between pre- and post-dilation eyes (p = 0.65). However, pre-dilation eyes performed better when considering the slope of the thresholds as a function of contrast modulation ratios (pre: β = 0.13, post: β = 0.08, p=0.026). Monocular CS testing with the Pelli-Robson chart also demonstrated a decrease in performance with dilation (1.58 vs. 1.51, p=0.04).

Conclusions : The MDS is a novel tool that shows promise in evaluating contrast sensitivity and visual function. Decrease in MDS performance with dilation indicates a diminished ability of participants to adapt to more challenging stimuli at increasing contrast modulation ratios. This finding was corroborated by decreased performance on the Pelli-Robson CS chart post-dilation. Thus, MDS warrants further investigation in various eye conditions and future evaluations in clinical practice should be done pre-dilation.

This is a 2020 ARVO Annual Meeting abstract.