[Blue-sensitive VEP test in diagnosis of glaucoma]

Glaucomatous eye diseases can be associated in many cases with a disturbance of blue-color vision. Also visual evoked potentials (VEPs) can be altered in glaucoma. In the present study both tests were combined in order to increase the sensitivity of the method, i.e. the pattern VEP was examined under conditions isolating the blue-sensitive part of the visual pathway.

34 normals, 14 patients with ocular hypertension (OHT), 15 patients with a so called pre-perimetric primary open-angle glaucoma (PPOAG), and 32 patients with primary open-angle glaucoma (POAG) were examined by presenting in the onset-offset mode blue stripe patterns 1. without an adaptive background light (blue- "black" pattern = BB) and 2. with an intensive yellow adaptation light (blue-on-yellow pattern = BY) suppressing the red- and green-sensitive cones. Amplitudes and peak times of the onset response were evaluated.

BB responses are of positive, BY responses of negative polarity (inion-ear). In normals the latter responses are significantly larger and have a significantly longer peak time. While in the patients groups the BB responses were not significantly altered, the BY responses were significantly reduced only in POAG. The peak time was significantly delayed in both PPOAGs and POAGs. The BY peak time proved to be most significant: Sensitivity 87.1%, specificity 82.4%.

The recording of the VEP with blue stimuli presented under selective yellow adaptation is a sensitive test for early glaucoma diagnosis.