Disparity vergence differences between typically occurring and concussion-related convergence insufficiency pediatric patients

Abstract

This study sought to test the hypothesis that significant differences would be observed in clinical measures, symptoms, and objective assessments of vergence eye movements between children with typically developing convergence insufficiency (TYP-CI) and children with persistent post-concussion symptoms with convergence insufficiency (PPCS-CI). Data from age-matched binocularly normal controls (BNC) were used for comparison. Data from three groups of children 11 to 17 years of age are presented: BNC (N = 11), TYP-CI (N = 10), and PPCS-CI (N = 15). Clinical measures of vergence, accommodation, and symptom severity were collected. Symmetrical 4° disparity vergence eye movements were quantified with an eye tracker integrated into a head-mounted display (Oculus DK2). Peak velocity and final response amplitude of convergence and divergence eye movement responses were assessed. The mean near point of convergence (break) was more receded (worse), the amplitude of accommodation more deficient, and convergent and divergent peak velocities slower in the PPCS-CI group compared with the TYP-CI and BNC groups. These results suggest that PPCS-CI may be a different clinical entity than TYP-CI. Hence, more research is warranted to determine whether the therapeutic interventions that are effective for TYP-CI can also be used for PPCS-CI populations.

Keywords: Amplitude of accommodation; Convergence; Convergence insufficiency; Eye movements; Near point of convergence; Persistence post-concussion symptoms; Vergence.

Figure 1:

Mean with one standard deviation for primary clinical measures and the CISS score used to diagnosis convergence insufficiency. Near point of convergence break (plot A), positive fusional vergence (plot B), and CISS (plot C) for BNC (white bars), TYP-CI (grey bars), and PPCS-CI (black bars) groups. The triangular lines denote the cut-off and direction of clinically defined normalcy. Significance is denoted as * (p<0.05) or ** (p<0.001)

Figure 2:

Group-level mean ±1 standard deviation (SD) position trace in degrees as a function of time (seconds) (solid line) and ±1 SD (shaded area) for the following groups:1) BNC (blue) convergence (2A) and divergence (2D), 2) TYP-CI (red) convergence (2B) and divergence (2E), and 3) PPCS-CI (green) for convergence (2C) and divergence (2F).

Figure 3:

Mean positional change in convergence (°) as a function of time (sec) (3A), velocity (°/s) as a function of time (sec) (3B), divergence mean positional change (3C), and velocity (°/s) as a function of time (sec) (3D) for BNC (blue), TYP-CI (red), and PPCS-CI (green) groups. The angular vergence demand alternated between 10° and 6° presented symmetrically on the participant’s midsagittal plane.

Figure 4:

Mean with one standard deviation for velocity (4A) and final amplitude (4B) for BNC (white bars), TYP-CI (grey bars), and PPCS-CI (black bars) for convergence and divergence responses. Significant differences of p<0.05 and p<0.001 are denoted with * and **, respectively.

Figure 5:

Histograms of convergence peak velocity (5A) and divergence peak velocity (5B) for BNC (white bars), TYP-CI (gray bars), and PPCS-CI (black bars) groups. The arrow denotes the median peak velocity.