Phenotypic Analysis of Intentionally Created Monocular Visual Field Defects During Bilateral Randomized Visual Field...

Background/Objectives: The imo Vifa^® is reportedly useful for diagnosing functional visual field loss; however, its potential for detecting malingering is unclear. Here, we intentionally simulated monocular visual field defects under bilateral randomized visual field testing conditions using the imo Vifa^® in healthy participants and compared their resulting defect phenotypes. Methods: Twenty participants (mean age, 37.3 ± 12.4 years; 12 orthoptists, 1 physician, and 7 administrative staff members) without ocular disease were enrolled. Four types of monocular visual field defects were simulated: right eye nasal hemianopia, left eye temporal hemianopia, right eye centripetal visual field constriction, and left eye central scotoma. Bilateral randomized visual field testing was performed using the AIZE-rapid mode with the 24-2 and 24plus(1) programs. Results: Accurate simulation of the intended defects was challenging. Orthoptists produced left homonymous hemianopia for right nasal hemianopia and left temporal hemianopia. Regarding right nasal hemianopia, many office workers generated patterns resembling right homonymous hemianopia-like, whereas for left temporal hemianopia, noncertified orthoptists produced patterns similar to those of left homonymous hemianopia-like. Considering the right centripetal constriction, all orthoptists produced the intended centripetal constriction, whereas non-orthoptists generated right homonymous hemianopia-like or patchy patterns. Orthoptists produced central scotomas or patchy patterns for the left central scotoma, whereas non-orthoptists generated left homonymous hemianopia-like patterns. Conclusions: Creating targeted monocular abnormalities during bilateral randomized visual field testing was challenging. Differences in the participants' understanding of visual field testing influenced the resulting patterns. In future research, having participants create monocular visual field defects under occlusion conditions would be necessary.