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Sabel & Gudlin report the results of a randomized, double-blinded placebo-controlled clinical trial (completed in 2007!) aimed to determine if behavioral activation of areas of residual vision using daily one-hour (two 30-min sessions) vision restoration training for glaucoma for three months improves detection accuracy compared with placebo. Thirtyfour patients with glaucoma (mean age: 61.7 years; range: 39-79 years) were initially randomized, but only 26 patients were included in the final analysis . The primary end point was change in detection accuracy in high-resolution perimetry. In the 'within group' analysis, the authors found that vision restoration training for glaucoma led to significant detection accuracy gains in high-resolution perimetry (P = .007) but not with white-onwhite or blue-on-yellow perimetry. Furthermore in the 'between group' analysis, the pre-post differences after vision restoration training for glaucoma were greater compared with placebo in all three perimetric tests respectively. An improvement in (faster) reaction time was also noted although vision-related quality of life was unaffected.
The authors propose a new rehabilitation treatment option for partial reversal of visual field defects in glaucoma patients and report that visual field defects caused by glaucoma can be improved by repetitively activating residual vision through training the visual field borders and areas of residual vision, thereby increasing their detection sensitivity.
Although these results are novel, several issues remain unanswered. The extent of improvement was very variable with one-third of patients not showing any improvement. The sample size and power calculation for the RCT has not been detailed with only 13 patients in each arm. The mean improvement in detection accuracy was within the mean test retest variability of the visual field. The influence of age, sex, baseline visual field damage, visual acuity, contrast sensitivity, type of glaucoma, etcetera on test results has not been evaluated. How long does the improvement last after cessation of training and would a change in the duration of training session have an impact on the results? The authors mention visual neural plasticity as a causative instrument in vision restoration, but have not included any objective parameter to evaluate this hypothesis. Despite these limitations, this pilot study offers a new hope for glaucoma patients and encourages further research into vision restoration training.