Clinical application of photopic negative response of the flash electroretinogram in primary open-angle Glaucoma

To evaluate the diagnostic performance of the photopic negative response (PhNR) for the detection of primary open-angle glaucoma (POAG).

Fifty-two normal subjects (52 eyes) and 173 POAG patients (173 eyes) were studied. The PhNR was elicited using a white stimuli on a white background. The mean deviation (MD) and pattern standard deviation (PSD) of the visual field were measured using standard automated perimetry (SAP). Spectral domain optical coherence tomography (SD-OCT) was used to measure the mean thickness of the retinal nerve fiber layer (RNFL).

In the glaucoma group, as compared to the normal group, the amplitudes of a-waves, b-waves and PhNR were significantly smaller (P<0.001), and the PhNR implicit time was significantly longer (P=0.004). The MD, PSD and mean thickness of the RNFL were significantly correlated with the amplitude of the PhNR (P<0.001). The area under the receiver operating characteristic curve (AUCs) for the amplitudes of a-waves, b-waves and PhNR were 0.853, 0.830 and 0.918, respectively. When the specificity was ≥ 95%, the sensitivities were 60.4%, 54.2% and 85.4% respectively.

The PhNR amplitude was reduced even when the loss in visual field sensitivity was mild, which suggests that PhNR might be a useful indicator of early glaucoma disease.