Background: Many studies reveal that neglect is a major cause of disability in stroke patients, and two months from onset neglect is still present in approximately 50% of individuals with a right brain lesion. Among the various methods of neglect rehabilitation, we have turned our attention to the prism adaptation treatment, developed by Rossetti in 1998. This treatment uses prismatic lenses, which produce a deviation of the fixation point of the visual field of 10 degrees to the right, 5 degrees below the coordinates of reference resulting from neglect.
Aim: To set out the possible effectiveness of less powerful lenses, we studied the response of a group of neglect patients treated with prismatic lenses that produce a deviation of the fixation point of only 5 degrees to the right, comparing them with a group of patients receiving placebo lenses.
Design: Randomized controlled trial.
Setting: Outpatients.
Population: The study involved 29 patients with left visual neglect.
Methods: All patients were assessed with a battery of seven visual-spatial tests. All patients were randomized by the pilot center and assigned to two different groups: "A" treated with pointing exercises and prismatic lenses of 5° to the right; "B" treated with pointing exercises and neutral lenses. Each group was treated with 5 rehabilitation sessions, lasting about 30 minutes each, from Monday to Friday for one week in the morning, by the same investigator, in each center.
Conclusion: The results showed that the prismatic lenses of only five degrees, used for the study, did not contribute to the variation in performance. Thus, this deviation of the fixation point of the visual field to the right is not sufficient to create a therapeutic effect. The improvement observed within the two groups, seems likely to be correlated with the pointing exercises, which force the subject to perform a visuomotor task with the healthy arm also in the neglected side.
Clinical rehabilitation impact: We believe that in order to carry out an effective treatment with prismatic lenses they must have a grade of at least 20 prism diopters. Lower grades are unable to determine an effect. Finally, because of the severe impact of neglect on the work of the rehabilitation team, and since our data shows that only five sessions are sufficient to demonstrate a change in performance, we believe that it is appropriate to use this method, especially in the acute phase of the disease.