Abstract
Purpose: :
To investigate diagnostic ability of the photopic negative response (PhNR) of the full-field and focal electroretinograms (ERG) in detecting glaucomatous eyes at various degree of visual field defect.
Methods: :
One hundred eyes of 73 patients with open angle glaucoma and 40 eyes of 40 normal controls were studied. The full-field cone ERGs were elicited by red stimuli on a blue background. The focal ERGs were elicited by a 15° white stimulus spot centered on the macular region, or on the supero-temporal or the infero-temporal areas of the macula. The receiver operating characteristic (ROC) curves were determined for the PhNR of the full-field and focal ERGs.
Results: :
In patients with early and intermediate glaucoma, the areas under the ROC curves (AUCs) were significantly larger for the PhNR amplitude and PhNR/b-wave amplitude ratio of the focal ERGs than those of the full-field ERGs. In advanced glaucoma, there was no difference in the AUCs between the focal and full-field ERGs. The specificity was over 90% for the full-field and focal PhNR when using optimal cut-off values. The sensitivity was 94.3% in eyes with early glaucoma for the PhNR amplitude and PhNR/b-wave amplitude ratio of the focal ERG, respectively, while the sensitivity was 34.3% and 25.7% for the full-field ERGs.
Conclusions: :
These results indicate that the focal PhNR could be a good indicator in detecting early and intermediate glaucomatous eyes. However, in advanced glaucoma diagnostic ability of the full-field PhNR is equivalent to that of the focal PhNR.
Keywords: electrophysiology: clinical • ganglion cells • electroretinography: clinical