Duration 5min, Q&A 3min
Improved Visual Function of Tunnel Vision Patients by Eye-Movement Training: fMRI Study
To evaluate visual processing changes in concentric contraction patients (CCPs) who acquired improved reading capabilities by eye-movement training (EMT), we performed neuroimaging before and after EMT by using functional magnetic resonance imaging (fMRI).
Six patients (4 women and 2 men, ranging in age from 23 to 53 years) with bilateral concentric contractions caused by the pigmentary degeneration of the retina and age-matched six normal volunteers (4 women and 2 men) were recruited. For the present experiments the corrected visual acuities (near vision at 40-cm distance) of patients ranged from 0.16 to 0.7 in logMAR for Pre EMT, and from 0.16 to 1.0 for Post EMT. Fields of vision measured using the I/4 target of Goldmann perimeter were less than 8 degrees. This study was approved by the Kyoto University Graduate School and the faculty of the medical ethics committee and adhered to the tenets of the Declaration of Helsinki. All subjects provided written informed consent prior to participation.
The CCPs adhered to the following EMT routine for 8-10 months, although some modifications were added depending on the symptoms of the individuals. 1) Eccentric fixation training, 2) Pursuit training, 3) Binocular vision training, and 4) the above trainings were repeated several times for 5 minutes a day. The fMRI data was acquired on a 3.0-Tesla scanner while subjects performed reading tasks. In a separate experiment (prior to fMRI scanning), visual reading performance was measured based on the number of letters correctly read for 5 minutes.
Results and Conclusion
Before EMT, primary visual cortex activation areas of CCPs were 48.8% that the controls, whereas the number of letters read correctly for 5 minutes was 36.6% that of the controls. After EMT, the CCP activation areas either did not change or were slightly decreased, but the reading performance of 5 of 6 patients increased, which was 46.6% that of the controls (P < 0.01). After EMT, increases in the activity of the frontal eye field were observed in all patients, but increases in the activity of the parietal eye field were observed only in the patients who showed the highest improvement of reading capabilities. The improvement in reading ability of the CCPs after EMT is regarded as the result of the increased activity of both frontal and parietal eye fields, both of which play important roles in attention and working memory, as well as in the regulation of eye movements.
[ Keyword ]
concentric contraction / eye-movement training / functional magnetic resonance / frontal eye fields / parietal eye fields
[ Conflict of Interest ]