Persistent visual impairments following mild-to-moderate ischemic stroke

Abstract

Background: Vision is rarely appraised either acutely or during recovery, following acute ischemic stroke. Our previous study found significant deficits in visual function after 2 to 3 days in ~68% of hospitalized mild-to-moderate acute ischemic stroke (AIS) patients with no comorbid eye disease. The purpose of this study was to evaluate recovery in vision after 2-6 months in a subgroup of the original participants.

Methods: Visual assessments were performed within the first week of admission and 2-6 months later. Testing was achieved on an iPad and included visual acuity (VA), VA-in-noise, visual field, visual neglect, and time to complete an eye-hand coordination (EHC) task. All cases were radiologically confirmed, and 10 had left hemisphere lesions. The outcomes were compared to 20 age-matched healthy controls who were tested and retested over a similar duration using the same vision tests. The testing took 12 min.

Results: During the first week of admission, 19/20 (95%) AIS patients returned normal visual acuity (>6/12 VA, p = 0.11), yet 11/20 (55%) had reduced VA-in-noise (p < 0.000).Visual neglect was present in 2/20 cases. Visual field defects were present in 16/20 (80%, p < 0.001), with 7/16 (44%) being unaware of their visual field loss. All of the patients chose to use their dominant right hand despite 10 having left hemisphere lesions and 13/20 (65%, p < 0.001) returning longer times to complete the EHC tracing tasks. After 2-6 months of recovery, all stroke patients returned normal visual attention, although 3/20 (15%) continued to show reduced VA in the presence of noise masks. Seven out of 20 (35%) retained visual field defects, and 8/20 (40%, three right and five left hemisphere lesions) had visuomotor impairment. Posterior circulation territory strokes and left hemisphere lesions were more likely to result in a persistent visual field loss and visuomotor deficit.

Conclusion: Given that stroke is the leading cause of neurological disability affecting over 110 million people, our findings highlight the necessity for both acute and longitudinal vision assessments subsequent to mild stroke. Exposing the persistent limitations in visual functions could aid in identifying suitability for driving and the visuomotor rehabilitation of stroke survivors.

Clinical trial registration: https://www.ANZCTR.org.au/ACTRN12618001111268.aspx, identifier ACTRN12618001111268.

Keywords: Melbourne rapid field-neural (MRFn); UNSW Lee-Ryan Eye-Hand Coordination Test (SLURP); acute ischemic stroke; eye-hand coordination; vision; visual acuity-in-noise; visual field; visuomotor function.

Figure 1

Consort Diagram: Inclusion and Exclusion Criteria for our clinical trial.

Figure 2

Images of the test suite used on the iPad Tablet. (A): Optotype letter “C” shown with the MRFn acuity test: in high contrast (left) and dynamic noise mask (right). The participants’ task is to match the orientation of the “C” in the box at the top of the panel with the appropriate option at the bottom. High-contrast optotypes are shown first during visual acuity assessment, followed by the visual acuity-in-noise optotype. (B): Top right: Tracing of the shape “Rabbit” using the SLURP Eye-hand Coordination App showing the stylus used for tracking, the completed track (pink), and the blueish white track remaining to be done. (C): Outcome for a left hemianopia in a 66-year-old patient tested with the MRFn test grid which took about 3 min in both eyes. This modified grid has reduced vertical and horizontal extent (15° Å~ 21°) and four test points added near the fovea (0.8°)..

Figure 3

Change in visual function of the stroke cohort (n = 20) between acute assessment in hospital (i.e., unfilled circles on left) and at the exact retest time shown on the x-axis. Filled symbols at retest time indicate cases which remained beyond the worst control (gray area). The gray zone indicates the 95% confidence interval for age-similar controls. (A): Visual Acuity, (B): Visual acuity-in-noise, (C): Visual Field Mean Deviation (MD-dB), 3D: Eye-hand coordination time (s).

Figure 4

(A) An example of a 65-year-old stroke patient with a right inferior quadrantanopia that resolved by the time of retest. Top: Visual field measured during the acute phase of stroke on admission to the hospital (September 19, 2018). Bottom: Visual field measured at retest (December 12, 2018). (B) Stable visual fields measured from a patient showing a right superior quadrantic defect. This patient shows no change in their visual field 2.5 months after stroke as evident qualitatively and in the MD values. Top: Visual field measured during the acute phase of stroke on admission to the hospital; MD LE -10.98 and RE -6.66. Bottom: Visual fields measured at 2.5 months later return MD of LE -9.92 and RE -6.70.

Figure 5

MRF hemispatial neglect cancellation test.

Figure 6

Visual abnormalities observed acutely and after 3.5 months average recovery time (-R) in relation to the site of stroke lesion (i.e., right or left hemisphere and anterior or posterior blood supply). Y axis: visual function parameter, X axis: Acute and recovery site of lesion. The bar identifies the cohort mean.

Figure 7

Venn diagram: Association of vision changes at acute onset and on recovery in 20 cases of mild-to-moderate acute ischemic stroke.