Abstract
Abstract: :
Purpose: To evaluate the effect of a visual restitution training in patients with homonymous field defects by a special fixation-controlled microperimetric technique using a Scanning Laser Ophthalmoscope (Rodenstock SLO 101). Methods: 17 patients carrying out the NovaVision visual restitution training (see abstract Sabel B.A. et al., submitted to ARVO 2002) were investigated before and after a six months training by means of the SLO. We scanned triplets of dots directly onto the retina up to an eccentricity of 10° (Trauzettel-Klosinski and Reinhard, IOVS 1998; 39:2177-2186) to assess the vertical border of the absolute visual field defect. The triplets were presented for 120 ms, the spatial resolution was 0.5° horizontally and 1° vertically. Altogether 241 locations were tested in each eye. The patients´ retinas were monitored together with the stimuli in order to check the fixation throughout the entire investigation and during the offline evaluation. Only in the case of central fixation their answer was considered. The visual field was quantified by calculating the ratio of the number of absolute defects and the number of test points. The training effect E was defined as the difference between these two ratios. Results: With our method we were able to determine the border and the shape of the absolute visual field defects in 15 patients. Artifacts of unstable or eccentric fixation were eliminated by SLO fundus control. The training effect of all patients was E=0.02±0.05 (mean±SD) in the right, E=-0.008±0.06 in the left eyes. Two of 15 patients showed a slight training effect in one of their eyes: E=0.18 (right eye) and E=0.04 (right eye), respectively. Conclusion: We could not detect an explicit change of the shape of the absolute homonymous scotoma after the visual restitution training. The subjective improvements reported by the patients (see abstract Sabel B.A. et al.) may be caused by other effects like improvement in exploration strategies or other cortical adaptive processes.
Keywords: 485 neuro-ophthalmology: cortical function/rehabilitation • 624 visual fields • 432 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)