Shaban Demirel

Chris A Johnson9
Stuart K Gardiner9
Brad Fortune6
9Chris A Johnson
9Stuart K Gardiner
6Brad Fortune
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PURPOSE To describe a normative database for the multifocal VEP (mfVEP) and to evaluate specificity for a range of cluster criteria. METHODS One hundred persons (62 females and 38 males) with normal visual fields and ranging in age from 21.6 to 92.4 years participated in this study. Self-reported race in 80 of these 100 persons was 'White or Caucasian,'(More)
Peripheral resolution acuity for achromatic gratings is known to be limited by the density of the underlying ganglion cell sampling array. After confirming isolation of the short-wavelength sensitive (SWS) system using chromatic adaptation methods, we wished to determine if resolution is limited by blue/yellow ganglion cell sampling (evidenced by a(More)
PURPOSE Visual field testing uses high-contrast stimuli in areas of severe visual field loss. However, retinal ganglion cells saturate with high-contrast stimuli, suggesting that the probability of detecting perimetric stimuli may not increase indefinitely as contrast increases. Driven by this concept, this study examines the lower limit of perimetric(More)
PURPOSE Ordinary least squares linear regression (OLSLR) analyses are inappropriate for performing trend analysis on repeatedly measured longitudinal data. This study examines multilevel linear mixed-effects (LME) and nonlinear mixed-effects (NLME) methods to model longitudinally collected perimetry data and determines whether NLME methods provide(More)
Currently, global indices that summarize the visual field combine sensitivities on a logarithmic (decibel) scale. Recent structure-function models for glaucoma suggest that contrast sensitivity should be converted to a linear scale before averaging across visual field locations, to better relate sensitivity with the number of surviving retinal ganglion(More)
The purpose of the present study was to compare standard multifocal visual evoked potential (mfVEP) pattern-reversal responses with those produced by pattern-onset, pattern-offset, and pulsed pattern stimuli. mfVEP recordings were obtained from five normal subjects using VERIS and a 4-electrode array. The standard reversal stimulus had 2(15) m-sequence(More)
PURPOSE To test the hypothesis that specific locations and patterns of threshold findings within the visual field have predictive value for progressive glaucomatous optic neuropathy (pGON). METHODS Age-adjusted standard automated perimetry thresholds, along with other clinical variables gathered at the initial examination of 168 individuals with high-risk(More)
PURPOSE The "frequency-doubling" effect or illusion, in which the apparent spatial frequency of a grating appears to be doubled, is produced when a low spatial frequency sinusoidal grating is counterphase flickered at a high temporal frequency. This study examines changes in apparent spatial frequency of sinusoids of various spatiotemporal content after(More)
PURPOSE We determined whether longitudinal changes in retinal nerve fiber layer (RNFL) reflectance provide useful prognostic information about longitudinal changes in function in glaucoma. METHODS The reflectance intensity of each pixel within spectral-domain optical coherence tomography (SD-OCT) circle scans was extracted by custom software. A(More)
PURPOSE Automated perimetry does not produce reliable estimates of true psychophysical threshold in glaucomatous visual fields when the perimetric threshold falls below 15 to 19 dB. It may be possible to truncate testing at such locations and not use stimuli with very high contrast. However, this can only be recommended if it does not harm the ability to(More)