Purpose: To investigate the clinical use of the large-field pattern electroretinogram (PERG) as an adjunct test to the International-standard PERG in an unselected sequential cohort of patients referred for routine electrophysiologic assessment.
Methods: Pattern electroretinograms to both 15° × 11° (International Society for Clinical Electrophysiology of Vision Standard) and 30° × 22° (large field) checkerboard field sizes were recorded in 277 consecutive electrophysiology patients, aged 10-79 years. Most patients had additional tests including full-field electroretinogram, electrooculogram, multifocal electroretinograms, or cortical visual evoked potential. Patient data were compared with data from 27 control subjects.
Results: Satisfactory 2-field PERG data were obtained in 91% (N = 253) of patients; data from 24 patients (9%) were excluded because of poor compliance (n = 17) or nystagmus (n = 7). Standard PERGs were consistent with macular dysfunction in 44% of cases; large-field PERG revealed macular dysfunction in an additional 8% of eyes and helped to distinguish between localized central, predominantly paracentral, and widespread macular dysfunction. The results were consistent with multifocal electroretinogram and/or imaging studies on the same patients. In some patients with optic nerve disease, the large-field PERG provided clearer evidence of normal macular function than the standard PERG.
Conclusion: Routine use of the large-field PERG is a valuable complement to standard-field PERG testing in the evaluation and management of patients with different forms of macular or generalized retinal dysfunction and can be useful in patients with optic nerve disease.