June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
Temporal summation varies with visual field eccentricity for perimetric stimuli scaled to the area of complete spatial summation
Author Affiliations & Notes
  • Padraig Mulholland
    School of Biomedical Sciences, University of Ulster, Coleraine, United Kingdom
    NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom
  • Tony Redmond
    NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom
    School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
  • Margarita Zlatkova
    School of Biomedical Sciences, University of Ulster, Coleraine, United Kingdom
  • David Garway-Heath
    NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom
  • Roger Anderson
    School of Biomedical Sciences, University of Ulster, Coleraine, United Kingdom
    NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom
  • Footnotes
    Commercial Relationships Padraig Mulholland, None; Tony Redmond, None; Margarita Zlatkova, None; David Garway-Heath, Moorfields MDT (P), Carl Zeiss Meditec (F), Heidelberg Engineering (F), Reichert Technoloies (F), Ziemer Ophthalmic Systems AG (F), Pfizer Inc (F), Allergan (F), Allergan (C), Allergan (R), Alcon (C), Alcon (R), Bausch & Lomb (R), Merck (R), Santen (R), Quark (C), Teva (C), Topcon (F), OptoVue (F); Roger Anderson, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 3924. doi:
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      Padraig Mulholland, Tony Redmond, Margarita Zlatkova, David Garway-Heath, Roger Anderson; Temporal summation varies with visual field eccentricity for perimetric stimuli scaled to the area of complete spatial summation. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3924.

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

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Abstract

Purpose: Previous studies have found the limit of complete temporal summation (critical duration) to remain constant across the visual field, but these studies did not account/control for changes in spatial summation with increasing visual field eccentricity. We wished to investigate temporal summation as a function of visual field eccentricity with a standard perimetric stimulus and a stimulus scaled to the area of complete spatial summation (Ricco’s area).

Methods: Achromatic temporal and spatial summation functions were generated for five healthy subjects (median age 29 years, range 24-47), at 5°, 10° and 15° eccentricity in four diagonal visual field meridians. A Goldmann III stimulus (0.43° diameter) was used for temporal summation experiments and a 200msec stimulus was used for spatial summation experiments. Temporal summation experiments were repeated with a stimulus equal in size to Ricco’s area at each test location. Ricco’s area and the critical duration were estimated from the respective functions using an iterative two-phase regression technique. All stimuli were presented on a gamma-corrected achromatic CRT monitor running at 121 Hz with an adapting field of luminance 10 cdm-2.

Results: Ricco’s area was larger at greater visual field eccentricities (0.34 log units, x2(2) = 19.9, p<0.005). There were negligible differences in critical duration measurements across the range of eccentricities investigated with a Goldmann III stimulus (0.067 log units, x2(2) = 3.32, p = 0.19). Median (IQR) critical duration values at 5°, 10° and 15° eccentricity with the scaled stimulus were 35.4 msec (26.2, 44.3), 45.2 msec (34.6, 67.6) and 64 msec (42.8, 90) respectively. This increase was statistically significant (0.26 log units, x2(2) = 9.03, p = 0.011). Post-hoc Wilcoxon signed-rank analysis with Bonferroni correction reported a significant increase in critical duration estimates between 5° and 15° when examined using the scaled stimulus (z = -2.80, p = 0.005).

Conclusions: The critical duration increases with visual field eccentricity when the stimulus is scaled to the localized Ricco’s area. This may have implications for perimetric thresholds in regions where a Goldmann III stimulus equals or is smaller than Ricco’s area.

Keywords: 642 perimetry • 758 visual fields • 730 temporal vision  
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