Abstract
Background: Patients with visual field deficits following stroke or TBI can train their residual vision with VRT to obtain VF-size increases. These have been demonstrated using super-threshold or near-threshold perimetry (1–4), but not with laser-scanning ophthalmoscopy (5). We wished to study if eye movements and/or fixation are altered after vision restoration therapy.
Methods: Data were compared among different, independent studies with respect to eye movements, border position shifts and fixation behavior, including determination of the blind-spot position.
Results: SLO measurements did not reveal evidence for eye movements before and after VRT greater than 1–2 degrees (5). When analyzing the perimetric topography of the visual border position before and after VRT, border shifts were typically non-uniform: while in some areas VF border shifts clearly occurred, in other areas they did not. Also, the shift of the visual field border in most patients was much greater than the expected 1–2° caused by normal eye movements (max. of up to 30°). Furthermore, when different perimetry measures are compared, the border shift are not identical: while in some patients the border shift may be pronounced when a simple task is used (such as super-threshold perimetry), no border shift occurs when a difficult task is used (such as the SLO). Both the blind spot position and fixation quality measurements collected with standard perimetry remained unchanged after VRT.
Conclusion: VRT does not affect eye movements nor fixation in any significant way. Detection of visual stimuli in the previously blind field after VRT is due to true restoration of vision.