title: Measuring oscillatory potentials: Fourier analysis.
abstract: Studying the oscillatory potentials in diabetic retinopathy, the authors experienced several problems interpreting results of digital filtering. The main problem was the separation of the first potential from the a-wave, since their frequencies are within the same range. To improve the procedure of measuring implicit times and of calculating amplitudes, the filtering was started with a finite impulse response filter and followed by a fast Fourier transform. The power of the oscillatory potential was calculated by determining the dominant frequency in the Fourier transformed response and expressed in microwatts. A group of normal subjects was compared with a group of early diabetic retinopathy patients. It appears that even in pathological circumstances a quantitative expression of the oscillatory potential is possible.
authors.affiliation: Oogziekenhuis, Schiedamsevest, Rotterdam, the Netherlands.
authors.forename: K
authors.initials: K
authors.lastname: Van der Torren
authors.forename: G
authors.initials: G
authors.lastname: Groeneweg
authors.forename: G
authors.initials: G
authors.lastname: van Lith
mesh_terms: D000328:Adult; D000368:Aged; D003930:Diabetic Retinopathy / Q000503:physiopathology*; D004596:Electroretinography / Q000379:methods*; D005583:Fourier Analysis; D006801:Humans; D008875:Middle Aged; D010775:Photic Stimulation / Q000379:methods; D012016:Reference Values