May 1988
Volume 29, Issue 5
Free
Articles  |   May 1988
The black hole effect in perimetry.
Author Affiliations
  • J M Britt
    Department of Ophthalmology, University of Washington School of Medicine, Seattle 98195.
  • R P Mills
    Department of Ophthalmology, University of Washington School of Medicine, Seattle 98195.
Investigative Ophthalmology & Visual Science May 1988, Vol.29, 795-801. doi:
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      J M Britt, R P Mills; The black hole effect in perimetry.. Invest. Ophthalmol. Vis. Sci. 1988;29(5):795-801.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Light-emitting diodes (LEDs), mounted in drilled holes in the perimeter bowl, are used as stimuli in several automated perimeters. A concern is that these "black holes" might interrupt the otherwise uniform background illumination and cause inconsistent test results. A Dicon perimeter was modified by covering some of the LEDs with diffusing plastic. One eye of 41 normal volunteers was tested repetitively within the central 5 degrees of the visual field at the same 12 locations with both covered and uncovered LED stimuli. Higher variances of multiple threshold determinations were observed, significant at the 0.0005 level, when testing was done with uncovered LEDs. On average, the black hole effect contributed 0.8 dB to short-term fluctuation. The black hole effect is probably of minor clinical importance except in exacting quantitative perimetry.

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