Aging and the rehabilitation of homonymous hemianopia: The efficacy of compensatory eye-movement training techniques and a five-year follow up

Abstract

The specificity and effectiveness of eye-movement training to remedy impaired visual exploration and reading with particular consideration of age and co-morbidity was tested in a group of 97 patients with unilateral homonymous hemianopia using a single subject /n-of-1 design. Two groups received either scanning training followed by reading training, or vice versa. The third group acted as a control group and received non-specific detailed advice, followed by training of scanning and reading. Scanning and reading performance was assessed before and after the waiting period, before and after scanning and reading training, and at short-term (11 weeks on average) and long-term follow-up (5 years on average). Improvements after training were practice-dependent and task-specific. Scanning performance improved by ∼40%, reading by ∼45%, and was paralleled by a reduction of subjective complaints. The advice (=control) condition was without effect. All improvements occurred selectively in the training period, not in treatment-free intervals, and persisted in the short- and long-term follow-up over several years. Age had only a minor, although significant effect on improvement in reading after training; co-morbidity had no significant impact on the outcome of training. In conclusion, visual impairments associated with homonymous hemianopia can be successfully and durably reduced by systematic and specific training of compensatory eye-movement strategies. The improvements in compensation strategies were independent of subjects' age and of co-morbidity.

Keywords: Ageing; Homonymous hemianopia; Reading; Rehabilitation; Scanning; Short- and long-term follow up; Subjective midline; Visual search.

Fig. 1

A: Diagram of selection of subjects with homonymous visual field defects (HVFD). Missing compliance (n = 33): too poor health (n = 24; 72.7%) or lack of interest in treatment (n = 9; 27.3%). B: Diagram of assessments and treatment periods. Mean time between onset of hemianopia (T1) and first assessment (T2) was 25 weeks, and between T2 and T3 (waiting period) 12 weeks. Follow-up assessment (T5 in groups 1 and 2, T6 in group 3) were performed approximately 11 weeks on average after the end of treatment. For further details, see text.

Fig. 2

Course of practice with visual search (A) and text processing (B) in a patient with left- (filled symbols; P1) and with right-sided hemianopia (open symbols; P2). P1 started with visual search practice followed by practice with text processing, while P2 started with practice with text processing followed by visual search practice. Arrows in A indicate the three levels of task difficulty (a: parallel, b: mixed, c: serial search modes). Set size was 30 in all conditions. Symbols indicate mean response in 30 trials at different stages of practice (number of trials). In B, arrows indicate the four levels of difficulty (a: 4–5 letter words; b: 8–9 letter words; c: 12–13 letter words; d: 15–16 letter words). Symbols indicate percentages of correct responses in 20 trials at different stages of practice (number of trials). Task difficulty was increased after the patient has reached either a stable search time (∼1 s) in three consecutive training blocks in A, or at least 90% correct responses in three consecutive training blocks in B. Note the increase in performance in both practice conditions in the course of practice in P1 and P2. For further details, see text.

Fig. 3

Performance in reading and exploration tasks for the three groups across assessment times, showing reading speed in word per minute for the reading task (A) and cancellation time for the exploration task (B). The improvements shown by each group relative to their performance at the first assessment time are shown for reading (C) and exploration (D). Error bars are standard errors of the means.