Background/aims: To determine the sensitivity and specificity of the photopic negative response (PhNR) of the focal electroretinograms (ERG; focal PhNR) to detect glaucomatous eyes with different degrees of visual field defects.
Methods: One hundred and fourteen eyes of 114 patients with open angle glaucoma and 42 eyes of 42 normal controls were studied. The focal ERGs were elicited by a 15° stimulus spot centered on the macula, on the supero-temporal, and on the infero-temporal areas of the macula. The receiver operating characteristic curves were determined to obtain optimal cut-off values. Eyes were classified as being glaucomatous when their focal PhNRs were less than the cut-off values in either retinal area (combined criterion).
Results: The focal PhNR amplitudes were significantly reduced with an advance of glaucoma. In early glaucoma, the sensitivities of the PhNR measured for each retinal area ranged from 58.1% to 80.7%. The sensitivities were significantly increased to 90.6% and 96.9% for the focal PhNR amplitude and the focal PhNR/b-wave amplitude ratio, respectively, when the combined criterion was employed. The specificity was >90%.
Conclusions: Focal PhNRs have diagnostic ability in detecting early glaucoma with high sensitivity and specificity, especially when the combined criterion is used.