Photoconvulsive response in epilepsy query

[Gillian Lawson]

I have a question which is puzzling myself and my colleagues :-

Why does a photoconvulsive response on an EEG disappear when one eye
is covered during intermittent photic stimulation of epileptic
patients?

I'd be grateful if anyone could "throw some light" <g> on this, or
point me at some relevant references.

Gillian Lawson                        gilly.lawson at btinternet.com
Chief EEG Technician, Epilepsy Unit
Western Infirmary, Glasgow, Scotland