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Richard Gale, Rachel Woodall, Archana Airody, Andre Gouws, Heidi Baseler, Antony Morland; Functional MRI to objectively assess if the visual cortex is able to re-establish responsiveness following neovascular AMD treatment with anti-VEGF therapy. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4945.
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© ARVO (1962-2015); The Authors (2016-present)
Success of novel treatments to restore visual function such as retinal prosthesis and stem cells assume that the cortex remains responsive and topographically aligned to reestablished inputs. In a prospective observational study we tested the hypothesis that the visual cortex was able to re establish function following anti-VEGF therapy for neovascular age-related macular degeneration (nAMD).
10 participants with nAMD undergoing routine anti-VEGF NHS treatment underwent ETDRS visual acuity, Zeiss cirrus SD-OCT and functional Magnetic resonance imaging (fMRI) before (visit 1) and after 3 monthly initiation treatments (visits 2-4). Functional MRI data were acquired on a General Sigma HD Excite 3T MRI scanner. Gradient recalled echo-pulse sequences were used to measure T2-wieghted blood oxygen level-dependent (BOLD) data (vector mean projected amplitude). Based on anatomical criteria two regions of interest, 5 mm in diameter were chosen in each hemisphere from each participant. One was in the posterior occipital pole (PP) retinotopically representing the macula region and the second in the mid-calcarine (MC) representing a peripheral location. The BOLD response (BR) from the PP was controlled for the expected variation in intersession response by correcting it by the MC activity and also by the untreated eye to create a cortical response (CR) factor. Pearson correlation co-efficients were calculated between the treated eye VA and the Central Retinal Thickness (CRT) and the BOLD response. A two tailed probability was calculated and p < 0.005 was taken as statistical significance.
The Mean BR was highly variable over time (Table 1) and the mean CR response increased over time (Figure 2). The correlation between the treated eye VA and CRT was -0.473 (p=0.002), between the CR and VA was 0.236 (p=0.142), and between CR and CRT was -0.410 (p=0.009). These results were driven by one outlier and once excluded all correlations missed statistical significance.
Although individual cases showed an increase in cortical activity, response was highly variable. Further work is required to confirm the hypothesis that the visual cortex is able to re establish function following anti-VEGF therapy nAMD.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Table 1. Treated and untreated mean and standard deviation (SD) for BR.
Figure 1. Mean CR factor (y-axis) at visit 1 to visit 4 (x-axis).
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