Target Eccentricity and Form Influences Disparity Vergence Eye Movements Responses: A Temporal and Dynamic Analysis

Abstract

This study sought to investigate whether stimulation to the fovea or the parafovea with different color combinations influenced the temporal and dynamic features of 4° disparity vergence step responses. Twelve unique types of stimuli were displayed within a haploscope presented along the participant's midsagittal plane. Vergence eye movement responses from fifteen naïve participants were recorded using video-based infrared eye tracking instrumentation. Latency and peak velocity from left and right eye movement responses were quantified. Results show that the type of stimulus projection (foveal versus parafoveal) significantly (p<0.001) influences the vergence response latency but did not impact peak velocity. Vergence responses to eccentric circles with 6° eccentricity targeting the parafovea resulted in a significantly faster response latency compared to vergence responses to a cross with 2° eccentricity stimuli targeting the fovea. Results have implications for the stimulus design of a variety of applications from virtual reality to vision therapy interventions.

Keywords: Eye movement; target color; target eccentricity; target form; vergence.

Figure 1

A) Stimulus design used for the 12 observation (OBS) with respect to visual target and color.

Figure 2A

The haploscope design used to present stimuli in separate visual fields to participants. 2B: experimental protocol illustrating the presentation of stimulus and vergence eye movements induced utilizing a haploscope.

Figure 3

The effect of stimulus target type across color for (A) the left eye response latency and (B) right eye response latency.

Figure 3

The effect of stimulus target type across color for (A) the left eye response latency and (B) right eye response latency.

Figure 4

The effect of stimulus target type across color for (A) the left eye response peak velocity and (B) right eye peak response velocity.

Figure 4

The effect of stimulus target type across color for (A) the left eye response peak velocity and (B) right eye peak response velocity.

Figure 5

The effect of stimulus target type for the left-eye and right-eye movement response latency for the 2° foveal cross, and the 4° and 6° parafoveal eccentric circles targets stimulating 4° symmetrical vergence step movements.