September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Spatial summation across the 10-2 visual field in normals and age-related macular degeneration
Author Affiliations & Notes
  • Agnes Yiu Jeung Choi
    Centre for Eye Health, The University of New South Wales, Kensington, New South Wales, Australia
    School of Optometry and Vision Science, The University of New South Wales, Kensington, New South Wales, Australia
  • Lisa Nivison-Smith
    Centre for Eye Health, The University of New South Wales, Kensington, New South Wales, Australia
    School of Optometry and Vision Science, The University of New South Wales, Kensington, New South Wales, Australia
  • Nagi Assaad
    Department of Ophthalmology, Prince of Wales Hospital, Randwick, New South Wales, Australia
    Centre for Eye Health, The University of New South Wales, Kensington, New South Wales, Australia
  • Sieu K Khuu
    School of Optometry and Vision Science, The University of New South Wales, Kensington, New South Wales, Australia
  • Michael Kalloniatis
    Centre for Eye Health, The University of New South Wales, Kensington, New South Wales, Australia
    School of Optometry and Vision Science, The University of New South Wales, Kensington, New South Wales, Australia
  • Footnotes
    Commercial Relationships   Agnes Yiu Jeung Choi, None; Lisa Nivison-Smith, None; Nagi Assaad, None; Sieu Khuu, 2014/094035 A1 (USA) and 13865419.9 (EU) (P); Michael Kalloniatis, 2014/094035 A1 (USA) and 13865419.9 (EU) (P)
  • Footnotes
    Support  NHMRC 1033224; ARC DP11010471; UNSW ECR Grant 2015 P535430; Australian Postgraduate Award; Guide Dogs NSW/ACT is a partner in the NHMRC grant and also provided a supplementary PhD scholarship for AC and support for LN-S.
Investigative Ophthalmology & Visual Science September 2016, Vol.57, No Pagination Specified. doi:
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      Agnes Yiu Jeung Choi, Lisa Nivison-Smith, Nagi Assaad, Sieu K Khuu, Michael Kalloniatis; Spatial summation across the 10-2 visual field in normals and age-related macular degeneration. Invest. Ophthalmol. Vis. Sci. 201657(12):.

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

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Abstract

Purpose : The Goldmann (G) size III stimulus of the Humphrey Visual Field Analyzer (HVFA) is routinely used to assess contrast sensitivity across the visual field. However, reports on spatial summation characteristics of the 30-2 paradigm suggest that GIII tests outside complete spatial summation and using this stimulus may result in smaller differences in contrast thresholds between normal and those with ocular disease. The 10-2 paradigm is a highly relevant test for ocular diseases affecting the central 20-degree field but the spatial summation characteristics of this paradigm including the location of the critical area (Ac) and slope of partial summation are unknown. Thus we investigated spatial summation changes in the 10-2 paradigm between normal and those with age-related macular degeneration (AMD).

Methods : We measured thresholds for one eye from 37 normal subjects aged 20-62 years (mean: 36±11 years) using the HVFA 10-2 full threshold paradigm with GI to GV stimuli. Spatial summation curves were plotted for each test location by fitting data with a two-line fit and derived Ac and slope of partial summation. After verifying Ac and partial summation slope do not change with age, we converted subject data to 50-year-old equivalent using published and calculated location specific decade correction factors. We applied similar procedures to 11 patients with intermediate AMD (range: 61-80 years; mean: 71±6 years) and compared spatial summation characteristics of this group to normative data.

Results : Normative Ac was established for the 10-2 paradigm and found to increase with eccentricity, consistent with previous studies using other test paradigms. GIII stimulus always exceeded Ac and tested visual function within various stages of partial summation across the 10-2 paradigm. A bigger difference in contrast thresholds was generally observed between normal and AMD patients when using a test stimulus at or within complete spatial summation (GI or GII).

Conclusions : Normative Ac values indicate that GI and GII test sizes operate within complete spatial summation while the standard GIII stimulus operates across a range of partial summation in the HVFA10-2 paradigm. Our results suggest that using test stimuli at or within complete spatial summation reveals a greater loss compared to the standard GIII stimulus in the 10-2 paradigm in patients with intermediate AMD.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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