Determining Near Point of Convergence: Exploring a Component of the Vestibular/Ocular Motor Screen Comparing Varied Target Sizes.
John D Heick, Curt Bay
PMID 33604131WHAT IT FOUND
Measuring near point of convergence with a pen tip or small electronic device yields larger distances than using printed letters.
Because target size changes the result, clinicians must use the same tool for baseline and post-injury testing to avoid misclassifying healthy athletes as impaired.
Key findings
01The near point of convergence measured with a pen tip or the Bernell Vergel device was significantly larger than when using 12-point or 14-point font targets.
02Sixty-one percent of healthy participants exceeded the 5 cm threshold for abnormal NPC, suggesting this standard may incorrectly classify many non-concussed individuals.
03All four measurement methods showed excellent reliability across three trials, but limits of agreement varied by target size.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
Participants were healthy university athletes, so results may not apply to concussed patients or other populations. Visual history (such as astigmatism or other disorders) was not collected, which could have influenced NPC scores. Psychological factors like ADHD or dyslexia were not screened for. The study did not compare these methods against a gold-standard diagnostic outcome for concussion.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not assume that a larger NPC measurement indicates a new problem if you changed the target from a letter to a pen tip. The pen tip naturally produces larger distances, so this difference is likely due to the tool, not a decline in function.