To the Editor.
—I read with interest the article by Connolly et al, entitled "Rapid Recovery From Cortical Visual Impairment Following Correction of Prolonged Shunt Malfunction and Congenital Hydrocephalus."1 The authors indicated that the three patients had long periods of elevated intracranial pressure secondary to shunt malfunction. They did not indicate how they knew that the pressure levels were elevated. Perhaps the patients had prolonged periods of shunt malfunction leading to an increase in intracranial pressure because of the reluctance to invasively measure intracranial pressure. The authors did mention that visual evoked potentials were used for evaluations of the patients, but they did not indicate how these were obtained. Visual evoked potentials have been found helpful in noninvasively estimating intracranial pressure levels in patients with acute hydrocephalus in shunts.2,3