Editor,—The paper by Sandramouli et alsuggested that convulsions rarely, if ever, give rise to retinal haemorrhages.¹ This was based on a series of 33 patients with convulsions, none of whom would seem to have had retinal haemorrhages. The statistical analysis they undertook was based on Hanley’s rule of 3.² Its use can be summarised by their statement ‘It is a good estimate of the worst case that is compatible with the observed data’.

Applying the rule to the series …