Detection of amblyopia with P-VEP during chloral hydrate sedation.

A major limitation of methods presently used for detecting amblyopia in preverbal children and infants is their dependence on patient cooperation. In response to this problem, we have introduced the use of chloral hydrate sedation as a means of obtaining the pattern visual evoked potential (P-VEP) in uncooperative infants. Twenty-five infants were studied: 14 with clinically diagnosed amblyopia, four with questionable amblyopia, and seven with no clinical sign of amblyopia. In patients with known amblyopia, P-1 amplitudes from the amblyopic eye were greatly diminished when compared with responses obtained from the non-amblyopic fellow eye, with amplitude ratios ranging from 0 to 0.66 (mean 0.36). In contrast, P-1 responses from non-amblyopic infants were quite symmetrical, with amplitude ratios of 0.82 to 0.98 (mean 0.92). These results indicate that the P-VEP can be obtained during chloral hydrate sedation and that P-1 responses reflect the presence or absence of amblyopia. Performing P-VEP during chloral hydrate sedation thus holds promise as an important clinical tool for the diagnosis of amblyopia in uncooperative infants and children.