Modern societies are becoming increasingly dependent on electronics, leading to an increase in visual symptoms. Vergence endurance, the ability to sustain performance, may serve as a quantitative metric to complement symptom surveys to assess vergence performance during near visual tasks. To quantify vergence endurance, 48 participants, aged 15 to 23 years with normal binocular vision, completed a 15 min symmetrical disparity vergence step task to assess potential changes in peak vergence speed over the course of the experiment. Peak velocity, final amplitude, and the slope of the linear regression fit of the peak velocity as a function of stimulus recording were quantified for convergence and divergence responses using an eye tracker integrated in a virtual reality headset. Peak velocity was sustained by 63% and 69% of participants for convergence and divergence eye movements, respectively. Convergence and divergence responses were significantly different for peak velocity (p < 0.001) and vergence endurance (p < 0.03). The endurance metric tool has potential that may help shape future clinical applications for those with acquired brain injuries, including concussions or neurodegenerative diseases such as multiple sclerosis or Parkinson’s disease.
Hirani et al. (Tue,) studied this question.