Abstract
Purpose :
Visual Midline Shift (VMS) is one of the visual consequences observed in individuals post-stroke , but its prevalence and associations with other variables are unclear. This cross-sectional study explores the prevalence, degree and direction of VMS and the possible vision and non-vision variables that could be associated with VMS among post-stroke individuals.
Methods :
Ten participants (9 males,1 female) were recruited in Hong Kong and Canada. Adults (>18 years of age) who had experienced their first and only stroke within the previous 2 years and with no history of other neurological disorders or cognitive impairment were included. Horizontal visual midlines (VM) (at 25cm, 50cm and 100cm) and vertical VM (at 50cm and 100cm) were measured with a mechanical VMS gauge. A VMS was defined as a result outside previously determined normal ranges for people without stroke (Ding R., et al. ARVO Abstract 5343, 2023). Clinical VM were measured with a hand-held wand at 50cm. Participants’ general, ocular health and stroke history were recorded, and a battery of tests, including tests of visual acuity, cognition (MoCA-Blind), spatial neglect, visual extinction, visual field, ocular alignment, ocular dominance, subjective straight-ahead (SSA), and visual open loop testing, were conducted.
Results :
Horizontal VM ranged from -5° - 5.3° (mean=0.2°, SD=2.8°), and vertical VM ranged from -2.6° - 4.3° (mean=0.5°, SD=2.4°) at 50cm. Seven of 10 participants demonstrated a horizontal VMS at one or more testing distance, while 4 had a vertical VMS. Eight of 10 had a VMS in either horizontal, vertical or both directions. For 6 participants with a horizontal VMS, the direction of the shift was towards the affected side of the brain. More VMSs were detected with the VMS gauge compared to the wand, indicating that the VMS gauge may be more sensitive. One participant had a horizontal VMS and 1 participant had a vertical VMS with the hand-held wand.
Conclusions :
This preliminary study indicates a high prevalence of VMS among post-stroke individuals. This suggests that consideration of VMS is likely important in the clinical assessment of post-stroke patients. These results also indicate that a more sensitive testing method might be needed for clinical evaluation than the current method using a wand. Recruitment is ongoing, and subsequent analysis regarding the associations will be conducted.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.