Visual evoked potentials in optic nerve injury. Does it merit a mention?

The value of Visual Evoked Potentials (VEP) in the management of indirect optic nerve injury was prospectively studied in 128 patients. In fifty patients who were either unconscious, uncooperative or had massive black eye, preventing the assessment of vision, a light Emitting Diode (LED) was used to record visual evoked potentials. The initial VEPs were normal in 17, abnormal in 49 and absent in 62. All 17 patients with normal VEP showed visual recovery. Amongst the 49 patients with abnormal VEP, 43 (88%) showed improvement. In 62 patients, initial VEPs showed no response but, in 12 subsequent VEP recordings wave formation was demonstrated. Thus in 50 patients repeated VEP recordings failed to demonstrate wave formation, and none of them improved. This study, thus brings out the high predictive value of both positive and negative VEPs, and specially the role of LED.