Stroke damage to the primary visual cortex (V1) causes a loss of vision known as hemianopia or cortically-induced blindness. While perimetric visual field improvements can occur spontaneously in the first few months post-stroke, by 6 months post-stroke, the deficit is considered chronic and permanent. Despite evidence from sensorimotor stroke showing that early injury responses heighten neuroplastic potential, to date, visual rehabilitation research has focused on patients with chronic cortically-induced blindness. Consequently, little is known about the functional properties of the post-stroke visual system in the subacute period, nor do we know if these properties can be harnessed to enhance visual recovery. Here, for the first time, we show that ‘conscious’ visual discrimination abilities are often preserved inside subacute, perimetrically-defined blind fields, but they disappear by ∼6 months post-stroke. Complementing this discovery, we now show that training initiated subacutely can recover global motion discrimination and integration, as well as luminance detection perimetry, just as it does in chronic cortically-induced blindness. However, subacute recovery was attained six times faster; it also generalized to deeper, untrained regions of the blind field, and to other (untrained) aspects of motion perception, preventing their degradation upon reaching the chronic period. In contrast, untrained subacutes exhibited spontaneous improvements in luminance detection perimetry, but spontaneous recovery of motion discriminations was never observed. Thus, in cortically-induced blindness, the early post-stroke period appears characterized by gradual—rather than sudden—loss of visual processing. Subacute training stops this degradation, and is far more efficient at eliciting recovery than identical training in the chronic period. Finally, spontaneous visual improvements in subacutes were restricted to luminance detection; discrimination abilities only recovered following deliberate training. Our findings suggest that after V1 damage, rather than waiting for vision to stabilize, early training interventions may be key to maximize the system’s potential for recovery.

No abstract

Purpose of review Homonymous visual field defects are a common sequela of stroke, and are assumed to be permanent within a few weeks of the event. Because consensus about the efficacy of rehabilitation is lacking, visual therapy is rarely prescribed. Here, we review current rehabilitation options and strategies in the translational pipeline that could change these perspectives. Recent findings The mainstays of available therapy for homonymous visual defects are compensation training and substitution, which allow patients to better use their spared vision. However, early clinical studies suggest that vision can partially recover following intensive training inside the blind field. Research into the relative efficacy of different restorative approaches continues, providing insights into neurophysiologic substrates of recovery and its limitations. This, in turn, has led to new work examining the possible benefits of earlier intervention, advanced training procedures, noninvasive brain stimulation, and pharmacological adjuvants, all of which remain to be vetted through properly powered, randomized, clinical trials. Summary Research has uncovered substantial visual plasticity after occipital strokes, suggesting that rehabilitative strategies for this condition should be more aggressive. For maximal benefit, poststroke vision-restorative interventions should begin early, and in parallel with strategies that optimize everyday use of an expanding field of view.

Objective: To re-evaluate the longitudinal progression of stroke-induced homonymous visual field defects using strictly automated perimetry (Zeiss Humphrey Systems), rigorous inclusion/exclusion criteria, and quantitative analyses. Methods: A retrospective chart review of stroke patients diagnosed with "homonymous hemianopia", who underwent monocular Humphrey visual field (HVF) perimetry using the 24-2 SITA standard pattern from 2011-2019, was conducted at a large US academic medical center. Reliable tests (<20% fixation losses, false positives, and false negatives) were identified and analyzed with generalized estimating equations to extract temporal trends in perimetric mean deviation (PMD) and deficit area. Results: Of 532 patients with "homonymous hemianopia", sequential, reliable HVFs were only available for 36 patients in the right eye, and 30 patients in the left eye, ranging from 7 days to 58 months post-stroke. Both PMD and deficit area improved early, within the first 3 months post-stroke; however, this was followed by a subsequent decline in performance >1 year post-stroke. Changes were similar between eyes. Conclusion: We discovered that a large portion of occipital stroke patients do not receive comprehensive ophthalmologic follow-up and, even then, only a fraction of HVFs performed are reliable enough for rigorous analysis. Nonetheless, reliable HVFs in such patients confirmed early visual improvement after stroke, consistent with prior reports. However, in contrast with prior, qualitative reports, there was no stability of the deficit beyond 6 months post-stroke; instead, gradual worsening erased the initial spontaneous improvement, especially >1 year post-stroke.