Pattern VEP for glare sensitivity testing.

Conditions such as optic neuritis and cataract cause a patient to be unduely affected by glare and this occurs even though they may have normal visual acuity. A new test incorporating visual evoked potential (VEP) and glare sensitivity has been developed in Christchurch which shows promise for the objective assessment of such conditions. This report describes the methodology of the new technique and its application to the glare sensitivity testing of fifteen normal volunteers and ten patients with post optic neuritis. The effect of glare was expressed in terms of the glare disability score (GDS). This was defined as the percentage reduction in the amplitude of the P2 peak in the VEP waveform after glare was introduced. In these preliminary results, in spite of relatively good visual acuity, nine out of ten patients with a past history of optic neuritis showed elevated GDS values indicating that they were more sensitive to glare than the normal volunteers. In addition we report a dramatic reduction in the GDS of one patient with a lens opacity following extracapsular cataract extraction and the implantation of an intraocular lens.