REMOVAL OF OCULAR ARTEFACTS FROM THE HUMAN EEG.

For online removal of ocular artefacts (OAs) the recursive least-squares technique of parameter estimation was chosen. Problems of 'blow-up' and sensitivity to computer round-off errors were overcome by using the recursive form of the U-D algorithm. A microprocessor-based accessory, known as an ocular artefact remover (OAR), was developed to remove OAs automatically. It may be plugged into most EEG machines using the recorder sockets. The effectiveness of the OAR was investigated using normal subjects and patients. Satisfactory removal of OAs was obtained for normals at a variety of EEG sites. Results for patients showed that when OAs were present slow waves and spikes were sometimes reduced in amplitude but were not removed completely. It is concluded that the OAR is a useful aid in the examination of EEGs.