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Chris A. Johnson, Meghan Sievertsen; Effects Of Pupil Size, Refractive Error, Background Luminance And Room Lighting On Pulsar Perimetry Results. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5499.
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To evaluate the influence of variations in pupil size, blur (refractive error) background luminance and room illumination (room lights on versus room lights off) on the results of Pulsar Perimetry in normal subjects, and to assess the calibration accuracy of the Pulsar Perimeter.
The Pulsar Perimeter presents circular 5 degree two dimensional sinusoidal stimuli (bulls-eye target) of low spatial frequency (0.5 to 6.3 cycles per degree) and high temporal frequency (30 Hz counterphase pulse motion). Contrast sensitivity for detection of the target is determined at 66 visual field locations in the central 30 degrees radius. A Spectra Pritchard Photometer (Model 1980A) and a Spectrascan PR670 radiometer (Photo Research) were used to calibrate the luminance, contrast and spatial profile of stimulus and background conditions on the Pulsar Perimeter. One eye of 10 normal volunteers with normal vision were evaluated. Blur (refractive error) was evaluated up to 4 diopters, pupil size was varied from 1 to 4 mm and background and stimulus luminance were varied over a 3 log unit range, and room lights were turned on (50 cd/m2) and off (less than 0.1 cd/m2).
Once it was warmed up, the Pulsar Perimetry system retained stable and accurate luminance and contrast measures over the testing time and for a period of several days. Variations in pupil size did not affect contrast sensitivity measures (1.32 dB shift for 1 to 4 mm pupils, P> .05), but reductions in background and stimulus luminance as well as increasing blur produced significant decreases in contrast sensitivity (9.46 dB shift for 0 to 4 diopters of blur, and 16.96 dB shift for 50 to 0.05 cd/m2 background level, P<0.001 for both cases). With the exception of one condition, ambient room illumination did not affect contrast sensitivity measures.
The Pulsar Perimetry system has accurate and stable calibration properties and is relatively unaffected by changes in pupil size. Adaptation level and blur produce degradations in contrast sensitivity.
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