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Subject: electroretinogram Вот с выделенного момента я совсем запутался, помогите, кто в теме.Data Acquisition
Multifocal ERGs were recorded using the VERIS system (EDI, San Mateo, CA). Pupils were fully dilated (7 mm) using 1.0% tropicamide and 2.5% phenylephrine. After topical corneal anesthesia (0.5% proparacaine), a Burian Allen bipolar contact lens electrode was placed on the test eye and a ground electrode clipped to the left earlobe. Patients were positioned 33 cm from the stimulus monitor. Stimulus clarity was optimized by overrefraction, and then a final adjustment of test distance was made to maintain constant stimulus magnification (test distance, 33 cm for plano overrefraction). The stimulus was presented on a 17-inch monitor (Dotronix, Inc., New Brighton, MN), driven at a 75-Hz frame rate and consisted of an array of 103 hexagonal elements across a field subtending 44° horizontally and 40° vertically. White hexagons had a luminance of 185 to 200 cd/m2, and dark frames were 1 to 2 cd/m2, resulting in local contrasts of 98% to 99%. Each hexagon was temporally modulated between light and dark according to a binary m-sequence21 with a base interval of approximately 13.3 msec. Observers fixated a small gray spot in the center of the stimulus during 8-minute recording sessions (m-sequence exponent, 15). To improve fixation stability, the sessions were broken into 30-second segments with brief rest periods between each segment. Signals were amplified (gain, 106), band-pass filtered (10–100 Hz), and recorded with a sampling interval of 0.83 msec (16x per video frame). Recording segments containing two or more amplifier-saturating artifacts were discarded and rerecorded. Заранее огромное спасибо..
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