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A bedside test to determine motion stereopsis using the Pulfrich phenomenon
D S Mojon1, K M Rösler, H Oetliker
1Department of Ophthalmology, University of Bern, Switzerland.
Ophthalmology
|July 15, 1998
Summary
A new swinging pen test (SPT) effectively detects the Pulfrich phenomenon (PP), a visual disturbance caused by asymmetric visual delays. This simple bedside test aids clinicians in evaluating motion stereopsis dysfunction.
Area of Science:
- Ophthalmology
- Neuroscience
- Visual Science
Background:
- Asymmetric delays in the visual pathway can cause the Pulfrich phenomenon (PP), a stereoillusion impacting daily activities like driving and sports.
- Existing methods for PP detection can be cumbersome, necessitating a simpler clinical approach.
Observation:
- A novel bedside test, the swinging pen test (SPT), was developed to assess PP.
- The SPT involves manually oscillating a pen and was compared against a mechanical pendulum (MP) as the gold standard.
Findings:
- The SPT demonstrated strong correlation with the MP in quantifying PP in normal subjects (r=0.92) and patients with optic neuritis (ON) (rs=0.90).
- The SPT exhibited high diagnostic accuracy with a 100% positive predictive value and 92% negative predictive value.
- The established normal range for PP was determined to be -1.40 to 1.52 msec, with acceptable intraobserver (8.2%) and interobserver (10.5%) variability for the SPT.
Implications:
- The swinging pen test (SPT) offers a practical and valuable tool for bedside evaluation of motion stereopsis dysfunctions.
- This accessible method can aid in the early identification and management of conditions causing the Pulfrich phenomenon.