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Using diplopia as a warning of an inappropriate visual (ocular) accommodative response (WIVAR).
J S Wolffsohn1, G K Edgar, N A McBrien
1Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia.
Aviation, Space, and Environmental Medicine
|July 27, 2001
Summary
A warning system for inappropriate visual accommodative response (WIVAR) helps pilots maintain proper focus when using head-up displays (HUDs). This system aids in keeping accommodation more distant during flight training tasks.
Area of Science:
- Optometry
- Human Factors Engineering
- Aviation Psychology
Background:
- Over-accommodation, focusing closer than intended, is a known issue with head-up display (HUD) use.
- This can negatively impact visual performance and pilot situational awareness.
Purpose of the Study:
- To develop and evaluate a warning system for inappropriate visual accommodative response (WIVAR).
- To assess the system's effectiveness in mitigating over-accommodation during simulated flight conditions.
Main Methods:
- A warning system projecting two lines, creating physiological diplopia, was implemented on a HUD combiner.
- The system leverages the link between convergence and accommodation to signal focus errors.
Main Results:
- The WIVAR system significantly improved accommodative response, keeping focus more distant.
- Effectiveness was demonstrated during forward-looking infrared (FLIR) viewing, high cognitive workload, and Ganzfeld conditions.
Conclusions:
- Collimated HUDs promote a more distant focus, but WIVAR lines offer additional accommodative relaxation.
- The WIVAR system shows promise for enhancing visual performance and safety in aviation.