Abstract
Purpose :
Visual midline shifts (VMS) are experienced by some individuals post-stroke, but normative data are not available and associations with other variables are unclear. This cross-sectional study explored the relationships between the VMS and other vision and non-vision variables in healthy adults, as well as the repeatability of these tests. Normative data are presented, which has not previously been published for most of these tests.
Methods :
Ninety-three participants without a history of visual or neurological problems were recruited in Canada and Hong Kong. Each participant attended two visits. Horizontal and vertical VMS was measured with a mechanical VMS gauge at 50cm and 100cm, and clinical VMS was measured with a hand-held wand at 50cm. During the first visit, the line bisection test, ocular dominance, subjective straight-ahead, and visual open loop testing were also conducted. During the second visit, all assessments were repeated in Hong Kong while the participants in Canada repeated both VMS measurements. The demographic information (e.g., height, weight, age,) of the participants was also recorded.
Results :
No statistically significant correlation was found between the VMS gauge measurements and other vision variables for either visit (p>0.05) except for a significant correlation between the VMS testing with the gauge and clinical VMS for the vertical direction (Spearman’s rho=0.506, p<0.001). There were significant correlations between the absolute magnitude of the VMS and age for the first visit (horizontal direction: Spearman’s rho=0.274, p=0.008; vertical direction: Spearman’s rho=0.437, p<0.001), which meant that the range of the VMS increased with age. These tests were found to be repeatable, and normative data, based on 95% ranges, were tabulated.
Conclusions :
This study showed the VMS is not associated with the line bisection tests, ocular dominance, subjective straight-ahead, or visual open loop for participants with no history of a neurological event. Therefore, it may be processed by independent neurological processing. In addition, the range of the absolute VMS increases with healthy aging. This information has significance for understanding the origins of VMS and its clinical application, and the normative data will aid clinicians in diagnosis.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.