scholarly journals Reduction of collinear inhibition in observers with central vision loss using anodal transcranial direct current stimulation: A case series

2020 ◽  
Author(s):  
Rajkumar Nallour Raveendran ◽  
Amy Chow ◽  
Katelyn Tsang ◽  
Arijit Chakraborty ◽  
Benjamin Thompson
Keyword(s):  
Visual Cortex ◽  
Visual Processing ◽  
Vision Loss ◽  
Peripheral Vision ◽  
Case Series ◽  
Cortical Inhibition ◽  
Peripheral Retina ◽  
Central Vision ◽  
Direct Stimulation ◽  
Central Vision Loss

AbstractPeople with central vision loss (CVL) due to macular degeneration are forced to rely on their residual peripheral vision and often develop a preferred retinal locus (PRL), a region of intact peripheral retina that is used for fixation. At the PRL, visual processing is impaired due to crowding (cluttering of visual objects). The problem of crowding still persists when images are magnified to account for the lower resolution of peripheral vision. We assessed whether anodal transcranial direct stimulation (a-tDCS), a neuro-modulation technique that alters cortical inhibition, would reduce collinear inhibition (an early component of crowding) when applied to the visual cortex in patients with CVL. Our results showed that applying a-tDCS to the visual cortex for 20mins reduced crowding in three patients with CVL and that the effect was sustained for up to 30mins. Sham stimulation delivered in a separate session had no effect. These initial observations mandate further research into the use of a-tDCS to enhance cortical processing of residual retinal input in patients with CVL.

scholarly journals Assessing functional reorganization in visual cortex with simulated retinal lesions

2021 ◽  
Author(s):  
Holly D. H. Brown ◽  
André D. Gouws ◽  
Richard J. W. Vernon ◽  
Samuel J. D. Lawrence ◽  
Gemma Donnelly ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Processing ◽  
Vision Loss ◽  
Visual Stimulation ◽  
Retinal Lesions ◽  
Central Vision Loss ◽  
Central Disk ◽  
Mean Luminance ◽  
Cortical Regions ◽  
The Impact

AbstractMacular degeneration (MD) causes central vision loss, removing input to corresponding representations in the primary visual cortex. There is disagreement concerning whether the cortical regions deprived of input can remain responsive, and the source of reported cortical responses is still debated. To simulate MD in controls, normally sighted participants viewed a bright central disk to adapt the retina, creating a transient ‘retinal lesion’ during a functional MRI experiment. Participants viewed blocks of faces, scrambled faces and uniform grey stimuli, either passively or whilst performing a one-back task. To assess the impact of the simulated lesion, participants repeated the paradigm using a more conventional mean luminance simulated scotoma without adaptation. Our results suggest our attempt to create a more realistic simulation of a lesion did not impact on responses in the representation of the simulated lesion. While most participants showed no evidence of stimulus-driven activation within the lesion representation, a few individuals (22%) exhibited responses similar to a participant with juvenile MD who completed the same paradigm (without adaptation). Reliability analysis showed that responses in the representation of the lesion were generally consistent irrespective of whether positive or negative. We provide some evidence that peripheral visual stimulation can also produce responses in central representations in controls while performing a task. This suggests that the ‘signature of reorganization of visual processing’, is not found solely in patients with retinal lesions, consistent with the idea that activity may be driven by unmasked top–down feedback.

scholarly journals Cortical reorganization of peripheral vision induced by simulated central vision loss

2019 ◽  
pp. 2126-18
Author(s):  
Nihong Chen ◽  
Kilho Shin ◽  
Rachel Millin ◽  
Yongqian Song ◽  
MiYoung Kwon ◽  
...  
Keyword(s):  
Vision Loss ◽  
Peripheral Vision ◽  
Cortical Reorganization ◽  
Central Vision ◽  
Central Vision Loss

scholarly journals The contribution of central and peripheral vision in scene categorization: A study on people with central vision loss

2014 ◽  
Vol 98 ◽  
pp. 46-53 ◽  
Author(s):  
Miguel Thibaut ◽  
Thi Ha Chau Tran ◽  
Sebastien Szaffarczyk ◽  
Muriel Boucart
Keyword(s):  
Vision Loss ◽  
Peripheral Vision ◽  
Central Vision ◽  
Scene Categorization ◽  
Central Vision Loss

scholarly journals Assessing functional reorganization in visual cortex with simulated retinal lesions

2021 ◽  
Author(s):  
Holly D. H. Brown ◽  
André D. Gouws ◽  
Richard J. W. Vernon ◽  
Samuel J. D. Lawrence ◽  
Gemma Donnelly ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Processing ◽  
Vision Loss ◽  
Visual Stimulation ◽  
Retinal Lesions ◽  
Central Vision Loss ◽  
Central Disk ◽  
Mean Luminance ◽  
Cortical Regions ◽  
The Impact

Abstract Macular degeneration (MD) causes central vision loss, removing input to corresponding representations in the primary visual cortex. There is disagreement concerning whether the cortical regions deprived of input can remain responsive, and the source of reported cortical responses is still debated. To simulate MD in controls, normally sighted participants viewed a bright central disk to adapt the retina, creating a transient ‘retinal lesion’ during a functional MRI experiment. Participants viewed blocks of faces, scrambled faces and uniform gray stimuli, either passively or whilst performing a one-back task. To assess the impact of the simulated lesion, participants repeated the paradigm using a more conventional mean luminance simulated scotoma without adaptation. Our results suggest our attempt to create a more realistic simulation of a lesion did not impact on responses in the representation of the simulated lesion. While most participants showed no evidence of stimulus-driven activation within the lesion representation, a few individuals (22%) exhibited responses similar to a participant with juvenile MD who completed the same paradigm (without adaptation). Reliability analysis showed that responses in the representation of the lesion were generally consistent irrespective of whether positive or negative. We provide some evidence that peripheral visual stimulation can also produce responses in central representations in controls while performing a task. This suggests that the ‘signature of reorganization of visual processing’, is not found solely in patients with retinal lesions, consistent with the idea that activity may be driven by unmasked top-down feedback.

scholarly journals Visual acuity and anatomical changes following vitrectomy for epiretinal membrane foveoschisis: a case series

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Chaiyaphot Photcharapongsakul ◽  
Susama Chokesuwattanaskul ◽  
Janejit Choovuthayakorn ◽  
Voraporn Chaikitmongkol ◽  
Paradee Kunavisarut ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Epiretinal Membrane ◽  
Vision Loss ◽  
Case Series ◽  
University Hospital ◽  
Central Vision ◽  
Central Vision Loss ◽  
Anatomical Outcomes ◽  
Sd Oct

Abstract Purpose To evaluate the visual outcome and macular anatomic structures on spectral-domain optical coherence tomography (SD-OCT) of patients with epiretinal membrane (ERM) foveoschisis who underwent vitrectomy. Methods A retrospective cohort, interventional, case series. Participants Fourteen patients (14 eyes) with central vision loss from an ERM foveoschisis underwent vitrectomy at Chiang Mai University Hospital from 2017 to 2018 and had a follow-up period of 12 months. Interventions The 23G vitrectomy with ERM and internal limiting membrane (ILM) peeling was performed by a single surgeon. Main outcomes Best-corrected visual acuity (BCVA) and anatomic appearance on SD-OCT were assessed at the time of preoperative evaluations and post-operative follow-ups at 1, 3, 6, and 12 months. Results Fourteen patients with a mean (SD) age of 67.9 (7.9) years and a mean (SD) visual acuity (VA) of 0.6 (0.1) LogMAR units were included in this study. Significant VA improvements were observed at the 3-month (0.43 (0.14) LogMAR unit), 6-month (0.45 (0.16) LogMAR unit) and 12-month (0.37 (0.21) LogMAR unit) post-operative visits compared to baseline, all with P-values < 0.001. At month 12, there were vision improvements of ≥3 lines in 8 (57.2%) patients, vision improvements of 1 or 2 lines in 2 (14.3%) patients, vision remained at the same line of pre-operation in 3 (21.4%) patients, and vision decreased by 1 line in 1 (7.1%) patient. Regarding the anatomical outcomes, 13 (92.9%) patients achieved anatomical foveal restoration, while one had persistent intraretinal schisis at the 12-month follow-up. The median time to achieve a foveal restoration was 3 months. No significant visual impairments were observed post-operatively. Conclusion In patients with central vision loss from ERM foveoschisis, vitrectomy with ILM stripping tended to improve both visual and anatomical outcomes.

scholarly journals Driving Habits in Older Patients with Central Vision Loss

Ophthalmology ◽  
2014 ◽  
Vol 121 (3) ◽  
pp. 727-732 ◽  
Author(s):  
Sabyasachi Sengupta ◽  
Suzanne W. van Landingham ◽  
Sharon D. Solomon ◽  
Diana V. Do ◽  
David S. Friedman ◽  
...  
Keyword(s):  
Older Patients ◽  
Vision Loss ◽  
Central Vision ◽  
Central Vision Loss

scholarly journals Bilateral juxtapapillary choroidal neovascularization secondary to Birdshot chorioretinopathy -- case report

2021 ◽  
Author(s):  
Sania Vidas Pauk ◽  
Nenad Vukojević ◽  
Sonja Jandroković ◽  
Miro Kalauz ◽  
Martina Tomić ◽  
...  
Keyword(s):  
Case Report ◽  
Macular Edema ◽  
Choroidal Neovascularization ◽  
High Myopia ◽  
Vision Loss ◽  
Detailed Examination ◽  
Central Vision ◽  
Birdshot Chorioretinopathy ◽  
Central Vision Loss ◽  
The Right

Central vision loss, photopsia, floaters and macular edema in a highly myopic patient can easily be misrelated to high myopia complications. However, in atypical cases, detailed examination along with a thorough diagnostic is required to establish the right diagnosis, which is often beyond the limits of the condition originally considered.

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