Abstract
Purpose: :
To characterize the patient population referred for electrophysiological testing at a tertiary ophthalmology care center who were found to have supranormal multifocal electroretinograms.
Methods: :
Between 1999 and 2005, 355 patients had electrophysiological testing, including a multifocal electroretinogram (mfERG). The mfERG tracings were compared to controls obtained on the same mfERG apparatus. Supranormal mfERGs were defined as those having amplitudes greater than 2 standard deviations above the controls. Patients with supranormal mfERGs were identified and a chart review conducted to characterize these patients by demographics and ophthalmic diagnoses.
Results: :
A total of 52 patients with supranormal mfERGs were found. There were 36 women, and the age range was 17–84 years (51 +/– 16). The following diagnoses were found (non–exclusive). Twelve patients were on chloroquine–related drugs (10 hydroxychloroquine, 1 chloroquine, 1 quinine), 9 had soft macular drusen, 6 had retinal venous occlusions (4 branch and 2 central), 5 had acute zonal occult outer retinopathy, 3 had chronic glaucoma, 2 had multiple evanescent white dot syndrome, 2 had Stargardt's, 2 had central serous chorioretinopathy, and 1 was a carrier of X–linked ocular albinism. The remaining patients had indeterminate diagnoses.
Conclusions: :
Supranormal mfERG responses are more common than would be predicted by random chance and appear to be associated with certain specific diagnoses. Supranormal mfERG responses may represent early retinal dysfunction. Such responses may be a helpful clinical marker for diagnosis or monitoring of retinal disease.
Keywords: electroretinography: clinical • electrophysiology: clinical • retina