A Reliability and Comparative Analysis of the New Randomized King-Devick Test

Abstract

Objective: The King-Devick (K-D) test is a rapid visual screening tool that can assess underlying brain trauma such as concussion via impairments in saccadic rhythm. A new tablet version of the K-D test using randomized numbers is now available, but reliability for this new version and comparison to the traditional K-D test has not yet been reported. Known for learning effects in the test, the aim of this study was to determine test–retest reliability and to compare performance of the new “randomized” version to the “traditional” K-D test version. We hypothesized that the “traditional” K-D test would show a greater rate of improvement with repeat application, compared with the “randomized” K-D test. Methods: Using a cross-sectional, repeated measures design in a healthy university student cohort (n = 96; age 21.6 ± 2.8 years; 49 women, 47 men), participants were required to complete the K-D test twice with a one-week break between testing sessions. Participants were randomly assigned into a “traditional” group, where they completed a test–retest of the established K-D protocol, using the same numbers; or the “randomized” group, where they completed test–retest protocol using 2 different sets of numbers. Results: Reliability testing showed a strong intraclass correlation coefficient for both the “traditional” test group (control group; 0.95 [CI: 0.91–0.97]) and the “randomized test group” (0.97 [CI: 0.95–0.98]). However, contrary to our hypothesis, no differences were found between “traditional” and “randomized” groups for baseline (control: 42.5 seconds [CI: 40.2–44.9 s] vs randomized: 41.5 [38.7–44.4], P = 0.23) and repeated testing between groups (control: 40.0 seconds [37.9–42.1 s] vs randomized: 39.5 [36.9–42.0], P = 0.55), with both groups showing improved times with repeated testing (control: 2.1 seconds [CI: 1.1–3.2 seconds] and randomized: 1.9 seconds CI: [0.9–2.9 seconds], P < 0.001). Conclusions: The “randomized” version of the K-D test, using different sets of numbers, demonstrates good reliability that is comparable to the traditional K-D testing protocol that uses the same number sets. However, similar to the “traditional” K-D test, learning effects were also observed in the “randomized” test, suggesting that learning effects are not because of content memorization, but rather familiarity of the test. As a result, although either test format is suitable for sideline concussion screening or return to play decisions, comparison of data should be made to the individual's baseline rather than to normative data sets.

Spotlight on the Developmental Eye Movement (DEM) Test

“…This learning-effect problem also affects the King Devick test because it is very similar. 64 The repeatability and agreement of the KD test show the same general behavior. Correlations (ICC) were high, but there is a significant improvement in performance in the second administration (reduced time of execution).…”

Reliability of a Smooth Pursuit Eye-Tracking System (EyeGuide Focus) in Healthy Adolescents and Adults

“…The reliability of the EyeGuide was comparable to other eye movement cognitive tests (e.g., King–Devick). For example, studies in adolescent populations have reported moderate to good ICCs of 0.81 (95%CI: 0.73, 0.87) and 0.91 (95%CI: 0.86, 0.95) [ 32 , 33 ] and in adults, good ICCs of 0.95 (95% CI: 0.91, 0.97) and 0.91 (95%CI: 0.80, 0.96) [ 28 , 34 ]. The data in the present study are also consistent with previously published EyeGuide data.…”

“…Participants undertook testing in a quiet room, away from potential distractions. Participants were also allowed usual eyewear such as prescription contact lenses or glasses, following standard protocol from other eye-movement testing such as the King–Devick [ 28 ] as well as recommended protocol from EyeGuide. Each participant completed three trials with a 30 s rest between each trial to avoid potential fatigue.…”

Reliability and Validity of Inertial Sensor Assisted Reaction Time Measurement Tools among Healthy Young Adults

“…In this study, participants were recruited if they lacked a history of concussion and met all the exclusion and inclusion criteria. Furthermore, participants had a KD score of 40 ± 6.3, which is within the normal range of this demographic [ 59 , 60 , 61 ] to ensure sample homogeneity.…”