Abstract
Purpose: :
To evaluate a novel electronic shutter (AutOccluder) that permits rapid, complete monocular occlusion of vision in children for use in developing a visual acuity test that eliminates the order effect by interleaving presentations between eyes. This human factors study is aimed at determining if normal children will tolerate intermittent occlusion while watching a 60 second cartoon video.
Methods: :
The AutOccluder is similar in appearance to a ViewMasterTM, and utilizes LCD shutters developed for welders’ hoods as well as an ultrasound system to monitor the child’s head position. A child peers through the AutOccluder, which is mounted at eye level on an adjustable floor stand. The shutters silently switch on/off in less than 0.1 second and have sufficient optical density to achieve occlusion. A laptop controls the shutters, monitors the child’s head position, and communicates wirelessly with a second laptop programmed to display visual acuity optotype stimuli and fixation stimuli (videos, etc). We evaluated the child’s response to viewing a 60 second cartoon segment while the shutters went through a preprogrammed cycle. Occlusion alternated between a test sequence of No Occlusion (NO), Right Eye Occlusion (REO), NO, Left Eye Occlusion (LEO), NO, and a sequence of NO, LEO, NO, REO, NO. Changes occurred every 10 seconds. Twenty–four second and third grade students who were participants in a vision screening program that included visual acuity testing and autorefraction participated in this study.
Results: :
All children complied with the task. No change in ultrasound monitored head position was noted during testing, suggesting that no children demonstrated a startle response when monocular occlusion occurred.. When asked about the experience, most talked about movie content. Two children reported an awareness that the shutters were operating.
Conclusions: :
This exploratory human factors work suggests that children will tolerate alternating monocular occlusion using this system. Future work will involve a handheld version and use of visual acuity tests.
Keywords: screening for ambylopia and strabismus • visual acuity • clinical (human) or epidemiologic studies: systems/equipment/techniques