Title : Video-based endurance and dynamic testing for convergence insufficiency in mTBI: A proof-of-concept study
Abstract:
Background: Convergence insufficiency (CI) is common in traumatic brain injury (mTBI), causing headaches, blurry vision, reading problems and reduced quality of life. Standard near point of convergence (NPC) testing may miss subtle deficits. This proof-of-concept study evaluates a novel video-based method using endurance and dynamic convergence tasks to detect CI in mTBI, assessing reading endurance and adaptability to shifting visual fixations.
Objective: The objective of this proof-of-concept study is to evaluate a novel video-based method using endurance and dynamic convergence tasks to detect convergence insufficiency (CI) in traumatic brain injury patients, assessing its sensitivity and specificity in identifying reading endurance and adaptability deficits compared to standard near point of convergence (NPC) testing
Methods: A neurologist in private practice examined 30 mTBI patients with CI (difficulty reading up close, NPC >7 cm, Convergence Insufficiency Symptom Survey [CISS] score >21) and 30 controls (no TBI, NPC <7 cm, no visual symptoms, negative CISS), with informed patient consent. Two tasks were performed: (1) sustained fixation on a pen tip near the nose to test convergence endurance, and (2) rapid pen tip movement toward and away from the nose to assess fusion adaptability. Video analysis evaluated fusion failure (outward eye deviation).
Results: All 30 mTBI patients showed fusion failure, with 98% exhibiting deviation in the endurance task and 99% in the dynamic task. Conversely, 98% of controls maintained fusion. The endurance task revealed a failure to sustain eye convergence, linked to reading difficulties, while the dynamic task showed inability to maintain convergence during rapid fixation shifts, from far to near, oculo-motor convergence deficits not fully captured by standard NPC testing.
Conclusion: This proof-of-concept study demonstrates a novel video-based method for detecting convergence insufficiency (CI) in mTBI patients with high sensitivity and specificity. Assessing convergence endurance and adaptability offers a practical, cost-effective, time-efficient bedside diagnostic tool for doctors. Future studies will be required with a larger sample size in order to enhance diagnostic precision by validating specificity and quantifying eye deviation patterns.
